question_answer

If \[A={{\sin }^{2}}x+{{\cos }^{4}}x,\] then for all real x

A)  \[\frac{13}{16}\,\,\le \,\,A\,\,\le \,\,1\]                 

B)  \[1\le A\le 2\]

C)  \[\frac{3}{4}\le A\le \frac{13}{16}\]                  

D)  \[\frac{3}{4}\le A\le 1\]

E)  None of these