Question

When looking at the mating timetable below I can deduce the following:
The Peeper frog and the Leopard frog can easily interbreed because their mating activity occurs at almost the exact same time.
The Tree frog and the Bullfrog have a very small window of time to interbreed
between June 1 and July 1.
You tell me:
Which two amphibians (frogs and toads) on the mating timetable below do not interbreed?

peeper frog/bull frog
• [tree frog/green frogA]
• bullfrog/tree frog
• leopard frog/peeper frog