Choose the best answer to complete each of the following sentenes

Choose the best answer to complete each of the following sentenes:
1.I've got a headache.-....
A.You must take some aspirins
B.You mustn't stay in bed
C.You must stay up late
D.You mustn't take a rest
2.Mai was absent from class yesterday...... her sickness
A.Because
B.For
C.Because of
D.With