The sentence ‘You must hurry, or you will miss the train’ is a:

A Compound Sentence consists of two or more independent clauses joined by a coordinating conjunction (like 'or', 'and', 'but', 'for', 'nor', 'so', 'yet'). In the given sentence, 'You must hurry' is an independent clause, and 'you will miss the train' is another independent clause, connected by 'or'.

• A Complex Sentence contains one independent clause and at least one dependent clause.
• A Simple Sentence has only one independent clause.
• An Interrogative Sentence asks a question.

Therefore, the presence of two independent clauses linked by 'or' makes it a compound sentence.