If $$A = \sin^2 x + \cos^4 x$$, then for all real $$x$$:

A

$$\dfrac{13}{16} \leq A \leq 1$$

B

$$1 \leq A \leq 2$$

C

$$\dfrac{3}{4} \leq A \leq \dfrac{13}{16}$$

D

$$\dfrac{3}{4} \leq A \leq 1$$