Which function represents exponential decay?

An exponential function represents decay when its base is greater than 0 and less than 1. In choice A, the base is 2/3, so each increase of 1 in x multiplies the function’s value by 2/3, making it decrease. The negative bases in B and D do not represent standard exponential decay, and choice C has a base greater than 1, so it represents growth.

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