Ken, a C.P.A., charges an annual fee to all of his clients for his services. Ken's services sometimes include investment advice but no extra fee is charged for that advice. After he begins spending 30% of his time giving investment advice, he decides to advertise the availability of the investment advisory services. According to the Investment Advisors Act of 1940, Ken is subject to regulation as an investment advisor:[A] When he gives advice about specific securities to clients.[B] When he starts spending more than 25% of his time providing investment advice.[C] When he begins advertising the availability of the investment advisory services.[D] When he starts charging investment advisory clients different fees than those charged the accountant's clients.