Ans: C
Consider the equation of the straight line,
Consider the equation of the straight line,
$\begin{array}{rcl}
x – y & = & k \\
y & = & x – k
\end{array}$
Therefore, the slope of the straight line is $1$ which is positive, and the $y$-intercept is $-k$ which is positive. Hence, the answer is C.
