—Who is the woman that is watering flowers? Is it your mother?

—No, it _________be her. She went shopping just now.      [ ]

A. mustn't              

B. may not

C. can't                

D. needn't

小鼠仙台病毒的主要传播和扩散方式是：（）。

A.直接接触和空气传播

B.直接接触和经水传播

C.经水传播和空气传播

D.经食物传播和经水传播