In the following passage some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each blank.

Comprehension:
China is the largest producer of pork, but it (1) ______ a big problem at the moment. There is an epidemic (2) ______ is killing its pigs. The virus was first (3) ______ in August last year, but one million pigs have died by now. It is a (4) ______ virus and when a pig catches it, it dies. China thinks that one third of (5) ______ pigs are going to die by the end of this year.