In the following passage some of the words have been deleted. Read the passage carefully and select the correct answer for tile given blank out of the four alternatives.

One afternoon, a dozen Arizona State University students ( I ) _____________ to spend the morning calling cardboard, taping fans and assembling filters in an effort to (1) _____________ 125 portable air purifiers for local schools. That (3) _____________ morning, staff members at a homeless shelter in Los Angeles were setting (4) _____________ 20 homemade purifiers of their own, while in Brookline, Massachusetts, another DIY air purifier was whirring quietly in the back of a day care (5) _____________ as children played.