Politicians have discovered that social media sites work for campaigning. a, beautiful
b. beautifully

Politicians have discovered that social media sites work beautifully for campaigning.

Explanation:

Taking the two words given in the option, let's differentiate them.

First, beautiful is an adjective and can be used to describe a noun. On the other hand, beautifully is an adverb that is used to describe a verb.

Now, considering the given sentence, the word near the 'blank' is "work' which is a verb. And so, using "beautiful" is invalid, making "beautifully" the only other option to be used.

And, if we put "beautifully" in the black, it completes the sentence.

Thus, the correct answer is option b.

propioception;