Consider the following statements: Other things remaining unchanged, market demand for a good might increase if<br/>1. price of its substitute increases<br/>2. price of its complement increases<br/>3. the good is an inferior good and income of the consumers increases<br/>4. its price falls<br/><br/>Which of the above statements are correct?

1. Price of its substitute increases — Correct. When a substitute becomes costlier, consumers shift to this good, so demand increases.

2. Price of its complement increases — Incorrect. Complements are used together; if the complement becomes costlier, demand for this good usually falls.

3. The good is an inferior good and income of consumers increases — Incorrect. For an inferior good, higher income makes consumers buy less, not more.

4. Its price falls — Correct. A fall in the good's own price causes an increase in quantity demanded; in such UPSC questions this is often treated as increase in market demand.

Hence, the correct statements are 1 and 4 only.