Sam bought 100 shares of common stock on Twitter, Inc. (TWTR) at the price of $40.97 per share on June 1. Since then Sam has closely watched the monthly prices for TWTR: $45.19 on July 1, $49.75 on August 1 and $51.58 on September 1 of the same year. TWTR doesnt pay any dividend. Based on the stock performance over these three months, what is the standard deviation for monthly returns on TWTR?

A. 10.5%

B. 10.09%

C. 3.68%

D. 3.76%