The correct option is B Nadia screamed loudly to attract the crowd's attention.
Adverbs of manner usually go at the end of a sentence. Sometimes, when
the adverb isn't very important, or the object is too long, the adverb
goes in the mid-position of the sentence.
In the given sentence, the object "to attract the crowd's attention" is too long, hence the adverb 'loudly' is preferably placed after the verb it modifies, 'screamed'. Also, the underlined adverb modifies a noun, 'attention'. Hence the sentence needs to be changed and option A is incorrect. Using this explanation, option B is correct.
Option C is incorrect because the adverb is placed at the end. Even though adverbs are placed at the end itself, when the object is too long the adverb should be placed near the verb.
Option D is incorrect because adverbs of manner are not placed in front of the sentence.