Which two amphibians (frogs and toads) on the mating timetable below do not interbreed a b c or d

Question

peeper frog/bull frog
peeper frog/bull frog

[tree frog/green frogA]
[tree frog/green frogA]

leopard frog/peeper frog
leopard frog/peeper frog

bullfrog/tree frog

Answer 1

The two amphibians that do not interbreed are the peeper frog and the bullfrog, and the tree frog and the green frog.