A$50,000 investment earns 18% annually. if b represents the balance and t represents the number of years, determine an expression that gives the account balance, b, after t years. also, determine an equivalent expression that displays the effective monthly interest rate.

a) b = 5(1.18)t; b = 5(1.14)^12t
b) b = 5(1.18)t; b = 5(1.014)^12t
c) b = 5(1.018)t; b = 5(1.14)^12t
d) b = 5(1.18)t; b = 5(0.014)^12t