Question: Which statement best describes Peak Expiratory Flow (PEF) Monitoring? Question options: 1) It is useful in the diagnosis of asthma. 2) It can provide an early indication of uncontrolled asthma or even an asthma exacerbation. 3) It is expensive. PEF monitoring devices can only be used one time and cost over $100 per meter. 4) The higher your PEF number, the more serious your asthma.