AMR is a computer-consulting firm. The number of new clients that it has obtained each month has ranged from 0 to 6. The number of new clients has the probability distribution that is shown below. Number of New ClientsProbability 0.05 1.10 2.15 3.35 4.20 5.10 6.05 The standard deviation is _____. a. 21 b. 1.431 c. 3.05 d. 2.047