Two normal-looking fruit flies were crossed, and in the progeny, there were 202 females and 98 males.
a) As opposed to the expected sex ration of 1:1 in this case the ration seems to be 2:1.
b) The female could be heterozygous, for an X-linked recessive lethal allele, which would result in 50% fewer males than female.
c) Half of the female should be heterozygous, for lethal allele, whereas the other half should be homozygous, for non-lethal allele.
Thus, mating of F1 females determine the sex ratio of the progeny that could support the hypothesis.