Which of these describe a divergent plate boundary?
A. Two continental plates moving away from each other, forming a rift valley
B. Two oceanic plates rubbing against each other, forming a mid-ocean ridge
C. Two oceanic plates colliding, forming a volcano
D. Two continental plates colliding, forming a mountain range

A. Two continental plates moving away from each other, forming a rift valley

Explanation:

The google description is:

A tectonic boundary where two plates are moving away from each other and new crust is forming from magma that rises to the Earth's surface between the two plates.

Based on that you can infer that A. Two continental plates moving away from each other, forming a rift valley

is the best answer.

though getting a second opinion might be best cause I am no expert in this subject.

b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.