The fertilization in
frog
is called external fertilization. Why?

External fertilization usually occurs in aquatic environments where both eggs and sperm are released into the water Most external fertilization happens during the process of spawning where one or several females release their eggs and the male(s) release sperm in the same area, at the same time.
Typically, frogs lay eggs. This process usually occurs through external fertilization, where the female releases her eggs from her body into water. Then, the male releases his sperm to fertilize them In this case, the eggs are fertilized inside the female's body before they are released.