Options A and D are trying to confuse you.
The real identity that looks similar to them is
sin^2 x + cos^2 x = 1
Options A and D are both incorrect and are not identities.
From options B and C, option B is the correct one.
By definition we have:
sin x = opp/hyp
cos x = adj/hyp
tan x = opp/adj
If you divide sin x by cos x and simplify, you get opp/adj, which is exactly what the tangent is.
The answer is B.
