One similarity between the spread of christian communities and the spread of jewish communities in the period 600 b. c.e.–600 c. e.

Both Christian communities and Jew communities developed out of the desire to reform the perceived corruption of the tradition into which they were to place their beliefs on spiritual quest, cultural movement and personal realization characterized by a central figure. Both Christians and Jews depicted Jesus as their reformer.  

c.) biotic: snails; abiotic: temperature climate

yup! you are correct it is b.