Which of the following statements most directly supports the conclusion that x→0limxsinx=1?
a) For x near 0, 1≤xsinx≤cosx1, and both endpoint expressions approach 1 as x→0.
b) For x near 0, cosx≤xsinx≤1, and x→0limcosx=1.
c) For x near 0, 0<xsinx<1, and x→0lim1=1.
d) For x near 0, sinx<x<tanx, and x→0limsinx=x→0limtanx=0.