A math problem in senior one, in which G represents a correspondence, which means that the value obtained by x+2 through the correspondence of G should be connected with X.

F (x) = 2x+3, which means that X passes through the corresponding relation F, and the corresponding function value is 2x+3.

G (x+2) = f (x) = 2x+3, that is to say, the real number x+2 corresponds to the function value 2x+3 through the correspondence relationship g.

Note: here is no longer the independent variable x corresponding to the unique function value through the corresponding relationship g.

So according to g (x+2) = 2x+3.

Find the expression of g(x).

Let t=x+2,

Then x = t-2.

So g(t)=2(t-2)+3=2t- 1.

Because x is often used instead of t as an independent variable, all t is replaced by x,

So g(x)=2x- 1.

So the answer is C.