Si $y = 1 + x + \frac{x^2}{2!} + \frac{x^3}{3!} + \cdots + \frac{x^n}{n!}$, entonces $\frac{dy}{dx}$ es igual a:

1. [a.] $y$
2. [b.] $y + \frac{x^n}{n!}$
3. [c.] $y - \frac{x^n}{n!}$
4. [d.] $y - 1 - \frac{x^n}{n!}$