"He is often clumsy; on the other hand, he dances beautifully"
This one is the correct answer for a couple reasons:
One, the first one cannot be correct because the comma is used incorrectly. A comma can connect an independent clause (one that could be its own sentence) to a dependent clause (one that could not be its own sentence). The first part is an independent clause because it has a subject, 'He', and a predicate 'is'. The second part is also independent, so a comma cannot connect them.
Two, the third one is incorrect because the phrase 'on the other hand' is a prepositional phrase, so a comma must follow it.
Three, the second sentence is correct because the first section is an independent clause, and the second section is an independent clause as well. A semicolon can only connect two independent clauses. The comma is in the correct placement because it is after the prepositional phrase that I mentioned earlier.
I hope I helped, and good luck with your work!
