下列说法正确的是（　　）

A．-1是-1的平方根

B．1是1的算术平方根

C．（-1）²的平方根是1

D．4是2的平方根

—Did you remember to give Mary the money you owed her?

—Yes, I gave it to her _______ I saw her.

A．while

B．the moment

C．suddenly

D．at the moment