Question

X and Y are two type of animals. animal X undergoes external fertilization and Y under goes internal fertilization.
Find X&Y

Answer 1

Animal X may be frog or fish as only they can go under external fertilization. Animal Y may be any mammal like human, animals etc.

Hope it helps

Answer 2

X is hen, lizard (Aves, Reptiles)



and Y is Human, Dog, Cow etc (Mammals)