Which of the following pair(s) of functions are identical?
(A) f(x) = cos (2 tan-1x),g(x) = 1 - x2/1 + x2
(B) f(x) =2x/1 + x2 ,g(x) = sin(2 cot-1x)
(C) f(x) = tan x + cot x, g(x) = 2 cosec 2x
(D) f(x) = eIn(sgncot-1 x) , g(x) = eIn[]1+{x}
where sgn(⋅), [⋅], {⋅} denotes signum, greatest integer and fractional part functions, respectively.