Final answer:
In Biology, dynamic sex-role reversal is observed in Fish, specifically in two-spotted gobies. This type of sex change, known as sequential hermaphroditism, can result in protogyny or protandry.
Step-by-step explanation:
In the study of Biology, the species that exhibits dynamic sex-role reversal, particularly in two-spotted gobies, is c) Fish. This phenomenon of changing sex roles is found in certain fish species, where the traditional roles of males and females can be reversed or altered depending on various biological and environmental factors. For instance, individuals of some species can change their sex during their lives, a process known as sequential hermaphroditism. Protogyny refers to organisms that are female first, and protandry refers to those that are male first. An example of this is in oysters, which are born male and later can become female to lay eggs.