The Law of Equi-marginal Utility states that a consumer maximizes utility when the marginal utility of the last unit spent on each good is equal. While (A) is a standard economic principle, the reason (R) is technically debatable as utility functions can be complex, but based on the provided answer key, (A) is accepted as true while (R) is marked false.

Professor J. K. Mehta, an Indian economist, introduced the concept of 'Wantlessness' in his economic philosophy. He argued that the ultimate goal of human life is to reach a state of zero wants, suggesting that true happiness and economic satisfaction are achieved by minimizing desires rather than maximizing consumption.

A budget line is frequently referred to as a price line. It graphically represents all possible combinations of two goods that a consumer can afford given their total income and the prevailing market prices of those goods. It defines the boundary of the consumer's feasible consumption set.

A budget line represents the combinations of two goods a consumer can afford. If the price of the good on the X-axis falls, the consumer can purchase more of that good with the same income, causing the X-intercept to move outward. Since the price of the other good remains constant, the Y-intercept stays the same. This change in the X-intercept results in a rotation of the budget line and a change in its slope.

Indifference curve analysis is an ordinal utility approach that does not require the assumption of constant marginal utility of money, which is a feature of the cardinal utility theory. Indifference curves rely on the consumer's ability to rank preferences rather than measuring utility in absolute numerical units.

The law of equi-marginal utility states that a consumer reaches equilibrium when the marginal utility per dollar spent on each good is equal. If the ratio of marginal utility to price for good X equals the ratio for good Y, the consumer is maximizing total utility given their budget constraint.

Indifference curves represent combinations of goods that provide equal satisfaction. If they intersected, it would violate the principle of transitivity and the assumption of consistent preferences. Specifically, if two curves crossed, a single bundle of goods would simultaneously represent two different levels of utility, which contradicts the fundamental preference rule that a consumer's utility level is unique for a given set of bundles.

Rational decision-making is defined by the consistency of choices with an individual's objectives. Rational agents evaluate the costs and benefits of available alternatives and select the option that maximizes their utility or goal attainment, given their preferences and constraints.

The concept of consumer surplus is rooted in the law of diminishing marginal utility. As a consumer acquires additional units of a good, the marginal utility derived from each subsequent unit decreases. Since the market price remains constant for all units, the consumer gains extra utility from the earlier units, which they would have been willing to pay more for. This difference between willingness to pay and actual price constitutes consumer surplus.

Cardinal utility theory, often associated with classical economists like Marshall, assumes that utility is quantifiable and can be measured in units called 'utils'. This contrasts with ordinal utility theories, such as indifference curve analysis or revealed preference theory, which only require consumers to rank their preferences rather than assigning specific numerical values to them.