What is appropriate Subject meaning

Q7. Complete the following sentences by using appropriate SUBJECTS: -
a)_________contains a lot of protein.
b) ________is the largest mammal on the earth.
c) ________is running at a speed of about 120 km. per hour.
d)________ is a holy book of Christians.
e) ________has sentenced two years imprisonment to the culprit.
f)_________ will announce the result next week.
g)_________will remain closed on the occasion of Eid.
h)_________ should read newspaper every day.
i)__________is no more a planet now.
j)__________is knocking at the door.