Which of the following statements are equivalent to "If A then B"?

In other words, when we are asked to prove "If A then B", which of the following statements can we prove instead?

(Note that there can be one correct answer or more.)

a."If (not B) and A then contradiction"

b."If (not B) then (not A)"

c."If (not B) then A"

d."If A and B then contradiction"

e.If (not A) and (not B) then contradiction.

f."If B then A"

g.If A and B then contradiction.

h."If (not A) then B"

i."If (not A) and B then contradiction