The correct option is C.
The heart is part of the cardiovascular system. The heart pump the blood round the body several times in a day. The blood is made up of several types of cells which carry out specific function in the body, these include the white blood cells which serves as soldiers of the body. The lymph refers to the fluid that circulate throughout the lymphatic system. Both the blood and the lymph are carried round the body by the cardiovascular system during the process of circulation.<span />
A control variable is a scientific experiment in which the experimental element is unchanged throughout the experiment
a control group is a group in an experiment that does not receive the treatment by the researchers (untouched by them) and used to see the changes between the controlled group and that of the group that received the vial
hope this helps
Answer:
hydrosphere
Explanation:
definition: the hydrosphere is the sum of earth's water, in the ocean, the ground, on the surface, and in the air.