Final answer:
The correct sequence of transformations for a function undergoing a vertical stretch and a reflection in the x-axis is to multiply the function by a constant between 0 and 1 and keep the sign of the function unchanged.
Step-by-step explanation:
The correct answer is D) Multiply by a constant between 0 and 1; keep the sign of the function unchanged. When a function undergoes a vertical stretch, it is multiplied by a constant greater than 1. When it undergoes a reflection in the x-axis, the sign of the function remains unchanged. Therefore, the correct sequence of transformations is to multiply the function by a constant between 0 and 1 and keep the sign of the function unchanged.