Algebra-2

Question Analysis
This problem tests the student's knowledge of the range of the cosine function, which is a fundamental property.

Key Concept Explanation
The range of the cosine function is the set of all possible output values. For the standard cosine function, this range is .

Step-by-step Solution
1. Recall the definition of the range of a function.
2. The cosine function oscillates between -1 and 1, inclusive.
3. Therefore, the range is