Which of the following pairs of structures are an example of homologous structures

Well, a homologous structure is a bone or something else that is present in many different species that could point to a common ancestor. Since you do not have the examples in your question I will just give you some and hope that it helps you: 
The arm of a human, the wing of a bird or a bat, the leg of a dog and the flipper of a dolphin or whale. 

I hope this helped! Let me know if it did not! 
I hope you have a fantastical day!!XD