Krashen identifies three kinds of affective variables related to second language acquisition: （）.

A．motivation, self-confidence and anxiety

B．comprehension, acquisition and anxiety

C．input, competence and self-confidence

D．situation, motivation and self-confidence

一般播种的种子发芽率要求不低于（）。

A.98%

B.95%

C.90%

D.85%