Researchers want to test how alcohol consumption affects memory. To test this, 36 females between the ages of 18-22 are asked to memorize a list of 10 items before and after being given two shots of tequila. Half of the group is tested on Tuesday afternoon and half of the group is tested on Wednesday afternoon. On Wednesday afternoon, city workers are doing construction outside on the street to repair a pothole. The construction noise is an example of:a. a type of error b. an extraneous variable c. confounding d. bias