The fundamental cause of the peloponnesian war was . select one of the options below as your . . a) rome's attempt to expand into greece . . . b) sparta's fear and jealousy of the power and wealth of athens . . . c) alexander the great's conquest of the persian empire . . . d) athens's fear of sparta's growing empire in greece.

The fundamental cause of the Peloponnesian War was Sparta's fear and jealousy of the power and wealth of Athens.
When Athens created an alliance with Corcyra in 433, and started to besiege Potidaea, it threatened the position of Corinth.
Sparta also feared that Athens was becoming too powerful but tried to prevent war.

So,after reviewing the causes of the war,I have concluded the best answer to be be the choice :

B) Sparta's fear and jealousy of the power and wealth of Athens