— _____ Will you please say it again?

—Sure. I said that they were going shopping.[ ]

A. Pardon 

B. Don't mention it  

C. Never mind   

D. I 'm sorry

赖氨酸生产菌都属于高丝氨酸缺陷型，（）和（）是赖氨酸生产菌的生长因子。