Final answer:
The correct answer to the question about viral entry mechanisms is option C) Fusion, Receptor-mediated endocytosis. These are the two mechanisms used by viruses to enter host cells.
Step-by-step explanation:
The viral entry mechanisms into a cell typically involve either endocytosis or direct fusion with the cell membrane. Endocytosis is an active transport mechanism whereby cells internalize particles and can be classified into: phagocytosis, pinocytosis, and receptor-mediated endocytosis. In phagocytosis, large particles, such as bacteria, are engulfed by the cell. Pinocytosis, often referred to as 'cell drinking,' involves the uptake of fluid and dissolved substances into the cell. In receptor-mediated endocytosis, specific molecules called ligands bind to receptors on the cell surface, triggering the endocytosis of the ligand-receptor complex. On the other hand, fusion involves the merging of the viral envelope with the host cell's membrane, allowing the viral genome to enter directly.
For the question regarding the types of viral entry mechanisms, the correct option is C) Fusion, Receptor-mediated endocytosis. Both fusion and receptor-mediated endocytosis are utilized by viruses to enter host cells. Fusion allows the viral envelope to merge with the host cell membrane, while receptor-mediated endocytosis involves the virus binding to specific receptors on the host cell, triggering internalization.