What can the number 2.15 in regression (3.) in Question 2 be interpreted as? If D decreases its price by 1%, C's sales will go up by 2.15% If D increases its price by 1%, C's sales will go down by 2.15% If C increases its price by 1%, D's sales will go up by 2.15% If D decreases its price by 1%, C's sales will go down by 2.15%