In the following passage some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives._x005F_x000D_ In view of last year's H1N1 attack and prevailing ________________ weather conditions, the health department officials _______________ that the virus will turn more active by January end. In-charge, Integrated Disease ________________ Programme (IDSP), Dr Shah, said, "Virus is still active, but not in a major way. In coming months, it is likely to become more active. Last year too, virus had claimed lives in January and February. Therefore, we are _____________ as coming months might _________________ a challenge."_x005F_x000D_ Therefore, we are _____________

• A. vigilant
• B. open to
• C. on toes
• D. impulsive