Answer: exponential decay (choice B)
The variable x in the exponent tells us that this is an exponential function. The fact that the base 1/2 = 0.5 is between 0 and 1 indicates that the value of y will decay or get smaller as x increases. Visually, it graphs out a curve that goes downhill as you read from left to right.
side note: The function f(x) = 7*(1/2)^x can be written as y = 7*(0.5)^x. It has a horizontal asymptote of y = 0 meaning that the curve will get closer and closer to the x axis, but never actually touch it.
