Here's a good general rule to follow (on both the GMAT and in real life): if you're using the word "hopefully", you're probably using it incorrectly.

Hopefully is an adverb, so it generally modifies verbs (although adverbs can also modify adjectives and other adverbs). So, when you say "it hopefully will reduce", "hopefully" is modifying the verb "will reduce", not expressing your desire that the reduction will take place.

Pretty much the only time you could use "hopefully" properly is if you're modifying an emotion. For example, you could say "I sighed hopefully", meaning "my sigh expressed hope".

So, on the GMAT, it's extremely unlikely that "hopefully" will be part of the correct answer. Since the word is so commonly misused, the GMAT likes to frequently test it.

Accordingly, we can quickly eliminate A, C and D.

(E) has the awkward "such as aerosol cans do" (such as usually refers to things, not actions), so let's knock that one out as well. With only 1 choice remaining, we choose (B) hopefully!