Consider the function
$f:X\rightarrow Y$ and $g:Y\rightarrow Z$
then which of the following is incorrect ?
(A) If $f$ and $g$ both are injective then $gof :X\rightarrow Z$ is injective .
(B) If $f$ and $g$ both are surjective then $gof :X\rightarrow Z$ is surjective.
(C) If $gof: X\rightarrow Z$ is bijective then f is injective and g is surjective .
My Approach : For the (A) part since both f and g are one - one then I thought of some functions and hence came to the conclusion that $gof$ will be one - one . But I want to know some good and convincing approach for this question ...