An inactivating mutation in the progesterone receptor gene would likely result in .

Progesterone

Explanation:

An inactivating mutation in the progesterone receptor gene would likely result in the inability of the uterus to support pregnancy

Progesterone is a hormone which is released by the corpus luteum in the ovary of the female reproductive systemIt plays an important role in menstrual cycle and and helps in maintaining  the early stages of pregnancyThe progesterone prepares the body for pregnancy in the event that the released egg is fertilizedIf the egg is not fertilized, the corpus luteum breaks down, the production of progesterone falls and a new menstrual cycle begins

The answer is b) gene