Which sentence is punctuated correctly?

The correct answer is D because it correctly uses a comma before the conjunction 'and' to connect two independent clauses. This follows the rule of using a comma before a coordinating conjunction when combining two independent clauses. Option A is also a valid sentence, but it combines the two actions into one independent clause without a conjunction. Options B and C lack the correct punctuation or structure for joining two independent clauses. Therefore, option D is the only choice that punctuates the sentence correctly by correctly connecting two independent clauses with a comma and the coordinating conjunction 'and.'