Answer: is an indication that product demand is declining.
Step-by-step explanation:
The negative sign on the slope of the time-series trend equation simply explains that the product demand is declining.
A negative slope indicates that two variables are negatively related which implies that when the value of x increases, rhen the value of y decreases, and vice versa. When putting this in a graph, the line falls when the line that's on the line graph shifts from left to right.
The correct option is C