Final answer:
The question involves simple addition in mathematics, where 2 + 2 equals 4, which is answer choice D.
Step-by-step explanation:
The question asks us to calculate a basic arithmetic sum: 2 + 2. This type of question falls under the category of basic mathematics, often taught at the elementary level but certainly understood by middle school students. The correct answer from the options listed is D) 4.
Adding two units to another two units gives us a total of four units. This is an example of simple addition, where each '2' represents a quantity, and when combined, they produce a sum. This foundational concept in mathematics is critical for understanding more complex mathematical operations.