A certain principal has been invested into a savings account at the specified interest rate and interest type. An equation can be created to model that savings account. Which of the following statement is true?

A. An investment of $300 gaining simple interest at a rate of 2% can be modeled by the equation B = 300 + 2t.
B. An investment of $300 gaining compound interest at a rate of 4% can be modeled by the equation B = 300 x 1.04^t
C. An investment of $300 gaining simple interest at a rate of 6% can be modeled by the equation B = 300 + 60t
D. B. An investment of $300 gaining compound interest at a rate of 4% can be modeled by the equation B = 300 x 1.6^t