Why is one hemisphere of mars believed to be older than the other?

Witch one is it soo it the the question b.a,b,c,d

Which of the following best describes brazil's economy from 1650-1880? a. it gradually shifted to manufacturing as the industrial revolution progressed. b. it was based on mining. c. it was based on plantation agriculture, where slaves served as a labor force. d. it was based on small, family-owned farms.

The covers all of earth like a thin shell,but it is not a solid sheet of material.it is broken up into several large sections and many smaller ones. fill in the blank.