Hello momo, You use "a. audit" here. A cash flow statement is a financial statement that shows a company's incoming and outgoing money during a time period. A financial audit is the examination by an independent third party of the financial statements of a company resulting in the publication of an independent opinion on whether or not those financial statements are relevant, accurate, complete, and fairly presented. So those operating cash flow statements serve as a reliable measuring instrument (barometer) when the company conducts financial audits.They facilitate the auditor's role in examining and evaluating the company's financial situation.

The answer is "C". Health. The word "barometer" here is a metaphor. A barometer measure barometric pressure. The financial statement measure the company's financial health.