a. This set is clearly disconnected because Determinant map is a continuous function from $\mathcal{O}_n(\mathbb{R})$ to the discrete set $\{1, -1\}$
c. This set can be thought as $\mathbb{R^2}-\mathbb{Q^2}$ which is connected as poved here Proving $\mathbb R^2 \setminus \mathbb Q^2$ is connected
b. I'm confused with this option and can't think of any possible ways to justify. Please give some hint. Thank you.
