Which of the following sentences is most conventional in spelling, punctuation, and mechanics?

a. The new tax law will effect our accounting system; it also will have a major affect on our tax flow.

b. The new tax law will effect our accounting system; it also will have a major effect on our tax flow.

c. The new tax law will affect our accounting system; it also will have a major affect on our tax flow.

d. The new tax law will affect our accounting system; it also will have a major effect on our tax flow.