Question

which formed element is able to leave the bloodstream?
a red blood cell
b white blood cell
c platelet
d all of the formed elements can leave the bloodstream.

Explanation:

White blood cells (leukocytes) can leave the bloodstream through a process called diapedesis. They move out of capillaries to reach sites of infection or inflammation in the tissues. Red blood cells (erythrocytes) generally remain in the bloodstream as they are specialized for gas transport and have a biconcave disc shape that helps in their movement through blood vessels but not in leaving the bloodstream. Platelets (thrombocytes) are involved in blood clotting and also mainly stay within the bloodstream. So, only white blood cells can leave the bloodstream among the given options.

Answer:

B. White blood cell