Let f : A → B and g : B → C
S1: if f and g are injection fuction then composition function gof :A → C is an injection. ----> this statement true its well known property.
S2:If the function gof : A → C is surjection and g is an injection then the function f is a surjection.
here keypoint is g is injection fuction.
means that g(f(x) = g(y) -----> f(x) = y so that fuction f is surjection
S3:If h(a) = g(f(a)) and h(a) is onto then g must be onto, where ∀a, a ∈ A.
all of the statement true. its all property .