Answer
(d) spontaneous at low temperatures.
Work Step by Step
$\Delta G=\Delta H-T\Delta S$
The reaction is spontaneous when $\Delta G\lt0$.
$\Delta G\lt0$ when $T\Delta S\gt\Delta H$.
As both $\Delta S$ and $\Delta H$ are negative, $T\Delta S\gt\Delta H$ when $T$ is small.
Therefore, the correct option is (d).
