Assertion (A) The quantity of a commodity demanded invariably changes inversely to changes in its price. Reason (R) The price effect is the net result of the positive substitution effect and negative income effect.

The correct answer is: A. Both (A) and (R) are true

Assertion (A) is true because of the law of demand, which states that, all other things being equal, the quantity demanded of a good or service will decrease as the price of that good or service increases.

Reason (R) is also true because the price effect is the net result of the positive substitution effect and negative income effect. The substitution effect occurs when a consumer substitutes a good that has become relatively cheaper for a good that has become relatively more expensive. The income effect occurs when a change in the price of a good causes a change in the consumer’s real income.

Here is a more detailed explanation of each option:

• Option A: Both (A) and (R) are true. This is the correct answer because both assertion (A) and reason (R) are true.
• Option B: (A) is true, but (R) is false. This is not the correct answer because reason (R) is true. The price effect is the net result of the positive substitution effect and negative income effect.
• Option C: (A) is false, but (R) is true. This is not the correct answer because assertion (A) is true. The law of demand states that, all other things being equal, the quantity demanded of a good or service will decrease as the price of that good or service increases.
• Option D: Both (A) and (R) are false. This is not the correct answer because both assertion (A) and reason (R) are true.