Answer
See below
Work Step by Step
Assume that $x$ be the vector in $S$
We can write set $S$ as $S=\{x \in R^4:x=(x_1,0,x_3,2): x_1,x_3 \in R\}$
Since $(0,0,0,0) \notin S$, $S$ is not a subspace of $R^4$
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