The sex chromosomes of a female bird have:

The correct answer is Option (3) → ZW Chromosomes

In humans and Drosophila the female is XX and the male XY, so the male decides the sex. In birds the system is the other way round: the female carries two different sex chromosomes and the male two similar ones. So in birds the egg decides the sex of the chick.

Option (3) ZW Chromosomes — Correct. In birds, the female has two dissimilar sex chromosomes, Z and W, and so produces two kinds of eggs; the male is ZZ. So the female decides the sex of the offspring.

Note: A similar question was also asked in CUET (UG) 2025 on 14-05-2025 (Slot 2).

NCERT Extract:
Sex Determination – “… In some other organisms, e.g., birds, a different mechanism of sex determination is observed (Figure 4.12 c). In this case the total number of chromosome is same in both males and females. But two different types of gametes in terms of the sex chromosomes, are produced by females, i.e., female heterogamety. In order to have a distinction with the mechanism of sex determination described earlier, the two different sex chromosomes of a female bird has been designated to be the Z and W chromosomes. In these organisms the females have one Z and one W chromosome, whereas males have a pair of Z-chromosomes besides the autosomes.”