Answer:
The rate of interest earn by Josh is 66.67% during investment period.
B is correct.
Explanation:
John invested $12,000 in mutual funds and received a sum of $20,000 at end of investment period.
First we calculate the interest earn from mutual funds.
Interest = Received - Investment
Interest = 20000 - 12000 = $8,000
Rate of interest (ROI)

ROI

ROI = 66.67%
Hence, The rate of interest earn by Josh is 66.67% during investment period.