Final answer:
The domain of sine and cosine functions is all real numbers, and their range is confined to values between -1 and 1.
Step-by-step explanation:
The domain of both the sine and cosine functions is all real numbers, making option (a) the correct answer. These functions can take any real number as their input because they are periodic and continue infinitely in both the positive and negative directions along the x-axis. As for the range, sine and cosine functions can only take on values between -1 and 1. This property is due to the fact that these functions represent the y-coordinate (sine) and the x-coordinate (cosine) of a point on the unit circle, and thus they cannot exceed the radius of the circle, which is 1. Therefore, the range of both functions is values between -1 and 1, corresponding to option (d).