Endocytosis is an energy-using process. The answer is A.
Answer:
peptide antigens by MHC class II molecules
Explanation:
Helper T cells are activated by peptide antigens by MHC class II molecules. These antigens express on the surface of antigen-presenting cells (APCs). After activation, the T helper cells divide and secrete cytokines to assist the immune response.
When writing a hypothesis, you need to be able to say IF this, THEN this will happen.
