Consider the following scenario and determine which match is best: In order to maintain a strong competitive advantage in customer service, Capitol One has always tried to ensure that the number of people employed in their call centers exceeds the industry standard by a significant amount. By using this strategy, the customer will be put on hold for as little time as possible before they are connected with a representative. And, after conducting extensive research with customer focus groups, Capitol One determined that a "good" hold time should be somewhere around 17 seconds on average. To determine if the company was actually meeting the above standard, executive officers obtained a sample of 35 calls and the average hold time was revealed to be 19.63 seconds. The population variance is known to be 18.73 seconds. Estimate Capitol One's true mean hold time with 90% confidence.

A. Z interval for population average

B. Z interval for population average with 34 degrees of freedom

C. T interval for population average

D. Z interval for a population proportion with 34 degrees of freedom

E. none of the above are correct