I 15 =

A -1
B 1
C -i
d i

C. -i

Step-by-step explanation:

i^n is expondential. i^1 = i

i^2 = -1

i^3 = -i

i^4 = 1.

first, we define the variables:

x: number of years after 1950

f (x): amount of vinyl sold.

then, with the variables defined, we have:

68594 vinyl records were sold in 1958 > f (8) = 68594

91299 vinyl records were sold in 1961 > f (11) = 91299

38720 vinyl records were sold in 1952 > f (2) = 38720

161743 vinyl records were sold in 1967 > f (17) = 161743

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step-by-step explanation: