What is the domain of the sine function?

The domain of the sine function is all real numbers, which means that you can input any real number into the sine function. This is because the sine function is defined for every angle, whether in degrees or radians, and can take any real value as its input. The sine function maps these inputs to values between -1 and 1, but the inputs (angles) themselves can be any real number. Thus, the domain encompasses the entire set of real numbers.

Other options describe the range of values that the sine function can output, rather than the possible inputs. The range of the sine function is limited to values between -1 and 1, so stating a range would not correctly represent the domain of the function.