Let, $p:$ $a^2 + b^2 = c^2$ and $q:$ triangle T be a right triangle.
Given: “A sufficient condition for $q$ is $p$” which is same as “If $p$ then $q$” i.e. $p\rightarrow q$
- “If $q$ then $p$” i.e. “$q\rightarrow p$” which is not equivalent to the given statement (we can not comment).
- “If $p$ then $q$” which is equivalent to the given statement, hence Correct.
- “If $\sim p$ then $\sim q$” which is the inverse of the given statement hence it is also not equivalent.
- “$q$ only if $p$” means $p$ is necessary for $q$ i.e. “$q\rightarrow p$” which is also not equivalent to the given statement.
Therefore, $\textbf{B}$ is the correct option.