Let $S$ be the set consisting of all those real numbers that can be written as $p - 2 a$ where $p$ and $a$ are the perimeter and area of a right-angled triangle having base length 1 . Then $S$ is\\
(A) $( 2 , \infty )$\\
(B) $( 1 , \infty )$\\
(C) $( 0 , \infty )$\\
(D) the real line $\mathbb { R }$.