This is for Lean Six Sigma. Your answer will be liked thank you!

A call center for a financial services company tracks the number of seconds a caller must wait before speaking with an associate by using a measure called "customer time-on-hold". Which of the following might give rise to common cause variation in the data collected? An occasional 'system crash' reduces the number of associates handling calls by 50% for 40 minutes. There is a 30% decrease in call volume on national holidays. There is a wide range of experience and training among the associates handling customer calls. A flu virus in January reduces staffing at the call center by 75% for one week. Six of the company's top traders are arrested for diverting customer assets into their own private accounts. Concerned customers flood the company with calls