Experimental demonstration that genes are present in chromosomes was inferred from the:

a. nondisjunction of the X and Y chromosomes.
b. appearance of white-eyed males.
c. disjunction of the X and Y chromosomes.
d. segregation of the X and Y chromosomes.

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.