Answer
$\bf {Graph(a)}$
Work Step by Step
Since, we have $r(t)=ti$ and $-1 \lt t \lt 1$
This shows us that any point on the graph has the form of $(t,0,0)$ . Thus, the y and z intercepts are both $0$ and x-varies from $-1$ to $+1$, which makes a line segment along the $x$-axis.
Hence, the required answer is $\bf {Graph(a)}$
