In leghorn chickens colored feathers are produced by a dominant allele, c. white feathers are produced by the recessive allele, c. the dominant allele, i, of another independent gene inhibits expression of color in birds with genotypes cc or cc, giving them a white phenotype as well. a colored rooster is mated with a white hen and produces many offspring, all colored. give the genotypes of both parents and the offspring.

Basically the male will have CC, the hen will have cc, and neither of them will have I. The key thing is that _all_ the chicks are coloured.

The male must have at least 1 C to be coloured, and cannot possess the dominant I. The hen has cc and/or an I to not be coloured.

That one chick is coloured would tell you little - only that the hen couldn't have 2 inhibitor alleles because otherwise the chick would have to have one and it doesn't.

However, for all of many chicks to be coloured, that means that the hen can't have any inhibitor alleles (otherwise around 50% would be white for that reason alone).

So to be colourless, the hen must be cc. However, if the male had only 1 colour allele (ie it was Cc) that would still mean that 50% of the chicks would be Cc (daddy's 'c' and one of mummy's 'c's). 

Hope this helps please award :)

The correct answer is c