Answer:
A) Temperature
Explanation:
Given that there is a negative correlation between coat sales and ice cream sales.
This may be definitely not due to amount of traffic. Also population will not affect both sales in different ways.
Amount of precipitation also may not be appropriate
But option a temperature if we consider
when temperature is low, i.e. in cold season there is more demand for coats as people want warmth but ice creams are less sold as already it is cold.
During summer, ice creams are more sold but coats are less sold.
Thus temperature is the lurking variable