Answer
The alternative hypothesis $H_a:μ\gt2$ matches with (a); the null hypothesis is $H_o:μ\leq2$. See the attached graph.
Work Step by Step
The alternative hypothesis $H_a:μ\gt2$ means that μ takes on all values greater than 2, and that is represented by graph (a).
The null hypothesis is the opposite: $H_o:μ\leq2$. See the attached graph above.