Explain how conventional cells move in the ocean

Convection drives the Gulf Stream and other currents that turn over and mix up the waters in the world's oceans. Cold polar water is drawn down from higher latitudes and sinks to the ocean bottom, pulled down toward the equator as lighter, warmer water rises to the ocean's surface.

Explanation:

Ithink the answer is d.

This is what i did 45-5=4040÷4=10so there are 10 white marbles but am not sure is just a question that am not sure