Question

put the following in order of how convection currents in the mantle move.
i. the material that moved up cools and sinks back down into the mantle.
ii. the bottom layer of the mantle material rises and spreads horizontally.
iii. the mantle material near the core is heated
iv. the material nearest to the core becomes less dense.
a iv, iii, ii, i
b iii, iv, ii, i
c i, ii, iii, iv
d iii, i, iv, ii

Explanation:

Convection currents in the mantle start with heating of mantle material near the core (III). Heating makes the material less dense (IV). Less - dense material rises and spreads (II). After rising, it cools and sinks (I).

Answer:

B. III, IV, II, I