Assume the following is a true statement.

Question

If it is raining, I will carry an umbrella.

Which form of the original statement must also be true?

a- converse

b-- inverse

c- contrapositive

d- biconditional

My answer is c contrapositive

Answer 1

Right, if the statement is true, the contrapositive is true.

statement
If a cow, then a mammal

converse
If a mammal then a cow
who knows?

Inverse
If not a cow, then not a mammal
who knows?

Contrapositive
If not a mammal, then not a cow
TRUE

Answer 2

In other words if I am not carrying an umbrella, it is not raining.

The biconditional would be
I carry an umbrella if and only if it is raining.
However you might carry one even on a sunny day.