Customers arrive at a checkout counter in a department store according to a Poisson distribution at an average of 5 per hour. During a given hour, select the correct R command that will compute the probability that that at most 2 customers arrive? Select one: O a. 1 - dpois (2, lambda = 5) O b. ppois(2, lambda - 5) O c. 1 - ppois(2, lambda - 5) O d. dpois(2, lambda - 5)