Why do people of both jewish and christian faith trace the start of their religions to isaac?

a. they believe isaac is god's final prophet.
b. they believe moses and jesus are isaac's descendants.
c. they believe isaac wrote the old testament.
d. they believe isaac survived in the desert due to the of god.

   B. They believe Moses and Jesus are Isaac's descendants

Explanation:  Isaac is the second son of Abraham, whom he received with his wife, Sarah, after the visit of God and the promise that Sarah will bear his son, who will be an ancestor to the chosen people, and who inhabit the earth as a sand in the wilderness. Isaac had two sons, Esau and Jacob, of whom Esau was older, and he needed to receive a blessing for the heir, i.e. one who will extend the blessed line. However, Jacob bought the blessing from Esau for a meal, and with the help of his mother, Rebecca, he was able to receive the blessing from father Isaac'. Thus Jacob became an ancestor of the chosen nation, and he had twelve sons, of whom they became twelve tribes of Israel. Thus, Isaac is indeed the ancestor of all Jews, including Moses and Jesus Christ.

she will pay the extra amount

the answer would be c