The initial value of an exponential function is 1.8. The rate of growth is 4.2%. Which models the value of the function, y, over time t?
A. y=1.8(1.42)ᵗ
B. y=1.8+4.2ᵗ
C. y=1.8(1.042)ᵗ
D. y=1.8(4.2ᵗ)