The conflict between palestinians and jews in palestine centered around
a. differences in religion.
b. the claim by both groups that it was their homeland.
c. disagreements over borders.
d. the role of the british in palestine.

The conflict between Palestinians and the Jews has multiple aspects to it, but I would say that the primary and most important is:

b. the claim by both groups that it was their homeland. - correct answer!

As an extension of their dispute over the land in general they also in practice disagree about the borders, but the claim to the whole land is more important as the center of the conflict.