Which is a correct alternative way to write sentence 1, reproduced here: (12) "The humanities are becoming lost in a world increasingly focused on the 'real' subjects of math, science, medicine, and engineering."

This sentence order just flips the two parts of the sentence. The other answer options either make the sentence unnecessarily wordy and confusing or change the verb number. In this sentence, "the humanities" is referring to multiple disciplines, which makes it a plural noun, requiring a plural verb.