If an answer only names convection current but does not write its causes what weakness remains?

Correct answer: Explanation of thermal difference and density change will be missing

Naming convection currents alone is not a complete explanation. A convection current is a circular movement in a material caused by differences in temperature and density. Heated material generally becomes less dense and rises, while cooler, denser material moves downward. This continuous movement can help explain forces connected with the movement of tectonic plates.

If an answer only writes “convection current,” it gives the term but not the reason or process behind it. The missing points are the thermal difference and the resulting density change. River water, population, and crop production are unrelated to the basic cause being asked about. Therefore, option A correctly identifies the weakness in the answer.