Let $g_n(x) = \frac{nx}{1+n^2x^2}$, $x \in [0, \infty)$, let $n \to \infty$, then-
(a) $g_n \to 0$ pointwise but not uniformly.
(b) $g_n \to 0$ uniformly
(c) $g_n \to x$ for all $x \in [0, \infty)$
(d) $g_n \to \frac{x}{1+x^2}$ for all $x \in [0, \infty)$
Explanation: (a) is correct.