Choose the word or phrase that best completes the tendencies: Tet is a festival ... occurs in late January or early February

1. Choose the word or phrase ( a,b,c,d) that best completes the tendencies 
1.1 Tet is a festival...........occurs in late January or early February 
a. Whom b. What c. Which d. Who
1.2 I suggest that you...........work harder on your pronunciation 
a. Should b. Might c. Would  d. Could 
1.3 Mai is very tired. .............,she has to finish her assignment before tomorrow