Well A&B both say the same thing, open and C says line up and D says Align.
The full sentence would be
Abran las bocas translated to : open the mouths
Limpien el cepillo. (English) Go Clean the brush/toothbrush.(plural command)
In the question is says to choose a plural command affirmative, and the first answer is selection is ‘limpie’ which would mean I cleaned the brush but that’s not what we are looking for. Limpien el cepillo, the second option is the answer because is plural and a command affirmative.