If ( limₓ → π/2 -1/1 + sinx )​, then which of the following is equivalent?
a. ( limₓ → π/2 -1/1 + sinx )
b. ( limₓ → π/2 sinx - 1/1 + sin²x )
c. ( limₓ → π/2 secx )
d. None of the above