How do the changes in current of the Lower
Congo River affect gene exchange?

Most of the river is navigable but it cannot be reached from the sea due to the Livingstone Falls, a series of rapids on the river near its mouth.

Explanation:

answer; i believe that the correct answer is (light);

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.