Answer:
The answer is D. Digestion
Proteins that assist in the movement of substances across can be classified into two types which are:
<h3>What are Proteins?</h3>
These are biological molecule which consists of amino acid sequences and are involved in metabolic activities in the body.
They are also found in cells and help in the selective movement of molecules in and out of the cell.
Read more about Protein here brainly.com/question/10058019
Because our bodies work to fight off unknown substances like bacteria
<span>The independent variable is the only factor in the experiment that the scientist will change. The effect of the changes in this independent variable in regards to the effect on the dependent variable/s are then observed, and the outcome of the experiment will then be determined from this.</span><span />
