This problem gives you some practice identifying how more
complicated functions can be built from simpler functions.

Let [math]**1.** [math]**2.** [math]**3.** [math]**4.** [math]

A.[math]2 + x^3

B.[math]1 + x + x^3 + x^4

C.[math]1 + x^6

D.[math]1 - x + x^2