Which of the following is correct regarding ZW-ZZ type of sex determination?

Both 1 and 2

The correct answer is Option (3) - Both 1 and 2.

In ZW-ZZ type of sex determination, which is found in birds, some reptiles, and some fish:

• Females are heterogametic (ZW), meaning they have two different sex chromosomes (Z and W).
• Males are homogametic (ZZ), meaning they have two identical sex chromosomes (Z and Z).

This is the opposite of what occurs in humans (XY system), where males are heterogametic (XY) and females are homogametic (XX).

Thus, both the statements 1 and 2 are correct regarding the ZW-ZZ system.