Meg is in-charge of the "Call-Me" call center. She has data for the average time it takes the operators to answer a phone call, and would like to use control charts to analyze the data. Which of the following statements are true? 1. She should use variable control charts.
2. She should use attribute control charts.
3. If she plots this data in the right control charts, and observes that all points are within the control limits and there are no visible patterns in the data.

Then, she can conclude that the process is meeting the specifications set by Call-Me, in terms of the average time taken to answer a call, 99.7% of the time.

a. 1 and 3 only
b. None of the statements are true
c. 1 and 2 only
d. All the statements are true
e. 2 and 3 only
f. 1 only