Formation of syncytia and inclusion bodies are examples of:
a. entry methods of viruses into host cells
b. types of viral capsids
c. cytopathic effects of viruses acute viral infections

(c). cytopathic effects of viruses acute viral infections.

Explanation:

Cytopathogenic effect or cytopathic effect can be described as the structural changes in cells of host due to viral infection.

Some examples of cytopathic effects are:

-rounding of viral infected cell.

-formation of syncytia by fusion of adjacent cells and polykaryon development. During this, cell membrane or 4 or more host cells join together and form an enlarged cell with 4 or more nuclei.

-formation of cytoplasmic or nuclear inclusion bodies. Inclusion bodies represent abnormal, insoluble structures  formed in cytoplasm or nuclei.  

Thus, the correct answer is option (c).