The correct option is
A harshly
Reading the poem, we can say that the poet asks the wind to blow gently so that it doesn't damage anything. Throughout the poem, the poet talks about how the wind blows roughly and destroys things. In order to fill the second blank, let's find the synonym for 'roughly'.
Option A - 'Carelessly' is an adverb, which means to act without being cautious. It's not a synonym of 'roughly'. Hence, option A is incorrect.
Option C - 'Strongly' is an adverb, which means bravely or to do something with great strength. It's not a synonym of 'roughly'. Hence, option C is incorrect.
Option D - 'Calmly' is an adverb, which means doing something without agitation. It's not a synonym of 'roughly'. Hence, option C is incorrect.
Option B - 'Harshly' is an adverb, which means rough or unpleasant. Hence, we can say that '...because when it blows harshly, it breaks the shutters of the windows. Also, 'harshly' contrasts 'softly' and explains the first sentence. Thus option B is correct.