The Charles Schwab Corporation (SCHW) is one of the more innovative brokerage and finan- cial service companies in the United States. The company provided information about its major business segments as follows (in millions) for a recent year. Investor (Retail) Services Advisor Services Revenues Operating income before taxes Depreciation and amortization $6,200 2,475 203 $2,418 1,175 66 a. How do you believe Schwab defines the difference between the segments? b. Provide a specific example of a variable and fixed cost in the Investor (Retail) Services" segment. c. Estimate the contribution margin for each segment assuming that depreciation and amor- tization are the only fixed costs incurred. d. If Schwab decided to sell its advisory services accounts to another company, estimate how much operating income would decline