In the next year, you expect Westpac shares have a 20% chance of earning 10 percent return, a 50% chance of earning only 2 percent and a 30% chance of earning - 10 percent. Based on this, what is the standard deviation of Westpac's expected return? Select one: A. 7.211% B. 0.5 20% C. 0.000% D. 5.311%