It was with great delight that I read in your February _____ the letter to the Editor written by Prof. Johnson.

A．issue

B．printing

C．magazine

D．copy

长颈鹿的颈很长，按照达尔文的观点，其原因是

A．变异朝着有利于生殖的方向发展的结果

B．繁衍后代的需要

C．代代经常使用，吃高处的叶子的结果

D．自然选择的结果