Which of the following sentences is grammatically incorrect?

Question

Quizplus · Accepted Answer

Last summer we went to the Alps this year we feel like going to the beach is grammatically incorrect because it is a run-on sentence.
Run-on sentences are when two or more complete sentences are written as one sentence. Run-on sentences can be fixed by adding a dash (-), a semicolon (;), or a colon (:) between the two sentences. You could also add a coordinating conjunction with a comma (, but) or make them two separate sentences with a period (.).
Any of these would be considered correct:
Last summer we went to the Alps, so/but/and this year we feel like going to the beach.
Last summer we went to the Alps; this year we feel like going to the beach.
Last summer we went to the Alps - this year we feel like going to the beach.
Last summer we went to the Alps: this year we feel like going to the beach.
Last summer we went to the Alps. This year we feel like going to the beach.

Which of the Following Sentences Is Grammatically Incorrect