When the expected cash flow s –curve is above the cost performance base line the project manager should?

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Cash flows going above cost baseline - does it happen in reality ? 

If it happens , a PM should first do option A and then option B .

Option-A investigate the variance to determine if corrective reaction is required.

The variance is indicating that actual progress is behind the schedule (Baseline). It can be because of many reasons. It should be analyzed for necessary action. like increase resources etc.

A. investigate the variance to determine if corrective reaction is required.

since the scenario described is temporary,   PM should first investigate ( option A) and try to adjust to reflect the actual ( option c) if the variance is casued by uncontrollobale factors and if the variance still persists, then inform the senior management ( option B)

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With the choice - A*

B. An alert senior management of the new situation. Managers of senior management will consult with the estimator who worked bid. If everything is correct it is expected that the site will get a financial reward for good work.

Normally it's not going to be happened, by the way the method is to "investigate the varience to determine if corrective reaction is required". this investigation should be concluded to necessary actions, e.g, control contracts & resources, people extra hrs, some extra job requested by company, ...