Which function represents exponential growth with a y -intercept at 5 ?

An exponential growth function has the form f(x)=a·b^x, where b>1. Its y-intercept is f(0)=a, since b^0=1. In choice C, f(x)=5·2^x, so f(0)=5 and the base 2 makes it grow. Choice B grows too, but its y-intercept is 2, not 5.

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