C) Semicolon (;)

A semicolon is used to combine two independent clauses without a conjunction. An independent clause is a complete sentence that can stand alone and express a complete thought.

Here are the key points to understand why a semicolon is the correct punctuation mark:

1. Independent Clauses: Before understanding the use of a semicolon, it is important to know what an independent clause is. An independent clause is a group of words that contains a subject and a predicate and can stand alone as a complete sentence. For example, "I went to the store" is an independent clause.

2. Conjunctions: Normally, when combining two independent clauses, a coordinating conjunction like "and," "but," or "or" is used. For example, "I went to the store, and I bought some groceries." Here, the coordinating conjunction "and" is used to join the two independent clauses.

3. Semicolon Usage: However, in some cases, a conjunction may not be necessary or desired to join two independent clauses. Instead, a semicolon can be used to indicate a stronger connection between the clauses. For example, "I went to the store; I bought some groceries." Here, the semicolon replaces the coordinating conjunction.

4. Examples: Let's look at a few more examples:
- "She loves to read; he enjoys playing sports."
- "Alice is studying for her exams; John is working on his project."
- "I like to swim; my sister prefers to hike."

In all of these examples, the semicolon is used to combine two independent clauses without the need for a coordinating conjunction.

In conclusion, the correct punctuation mark to combine two independent clauses without a conjunction is a semicolon (;). It is used to indicate a stronger connection between the clauses while still keeping them separate.

A semicolon is used to connect two closely related independent clauses without a conjunction.