关于种群和群落的叙述，错误的是[ ]

A．种群密度是种群最基本的数量特征

B．“S”型增长曲线表示种群数量与时间的关系

C．群落结构的形成是自然选择的结果

D．火山喷发和火灾后的演替都属于初生演替

Why didn't you ask for help,____ trying to do it on your own? [ ]

A. rather than

B. other than

C. more than

D. less than