Structures are fully functional, show evidence of a common ancestor, and may or may not have the same function in different species

Homologous structures are fully functional, show evidence of a common ancestor, and may or may not  have the same function in different species

Explanation:

Homologous structures are structures that have arisen from a common ancestor. They might not look the same or perform the same function, but they have evolved from the same ancestor.

Examples include the forelimbs of vertebrates - think of the human forearm arm, bat's wing, horse's leg, and dolphin's fin. These all look very different and perform entirely different functions, but they evolved from a common ancestor.

the answer is c.) there is a warm front in region a and a stationary front in region b.