1. If the graph of the inverse proportion function $y=\frac{k}{x}$ intersects the line $y=4 x-1$ at a point $P$ with an x-coordinate of 1, then $k$ $=(\quad)$.
(A) -3
(B) -1
(C) 1
(D) 3
-.1. D. From the condition $P(1,3) \Rightarrow 3=\frac{k}{1} \Rightarrow k=3$.