Option C tells about possible Mutation of virus, so we do not know in the new state Virus pose any threat or not
(C) is correct IMO
At human body temperature, the influenza virus can remain infectious for approximately one week. Because the virus becomes inactive in the human body after one week, an infected person cannot be held responsible for any transmission of the virus after that time has elapsed.
The conclusion is most weakened by which of the following, if true?
(A) The influenza virus is sometimes confused with the unrelated gastroenteritis.
(B) The influenza vaccine is highly effective in preventing transmission of the influenza virus.
(C) Because the influenza virus mutates, a vaccine that is effective in preventing transmission of the virus one year may be ineffective a year later.
(D) The influenza virus can remain infectious for longer than a week at temperatures below that of the human body.
(E) Generally, those most susceptible to life-threatening illness as a result of the influenza virus are children, the elderly, and those with compromised immune systems.