Final answer:
The correct option is a). An organism that changes from female to male exemplifies sequential hermaphroditism, specifically protogyny. This is commonly seen in certain fish like wrasses and in some species of oysters.
Step-by-step explanation:
An organism that starts out its life as a female but later changes into a male exhibits a form of sequential hermaphroditism. Sequential hermaphroditism occurs in certain species where individuals can change their sex during their lifetime. If the individual is female first and becomes male later, this is called protogyny. Conversely, if it is male first and becomes female later, it is known as protandry. Organisms like some species of wrasses and oysters exhibit this reproductive strategy. In contrast, simultaneous hermaphroditism occurs when an organism possesses both male and female reproductive parts at the same time, while monoecism refers to individual organisms that possess both reproductive systems but do not change sex. Dioecism describes species with distinct male and female individuals.