How does one determine the sex ratio of a ZZ and ZW cross?
Let $Z$ be the chromosome carrying the non-lethal dominant allele, and $Z_l$ the chromosome carrying the lethal recessive allele.
The Punnett square goes:

$Z_lW$ is not viable, so there are two possible male genotypes ($ZZ$ and $ZZ_l$) and only one possible female ($ZW$). So the correct answer is A. indeed.