Jack consumes two slices of pizza and drinks two large glasses of soda. Half an hour later, he complains of a stomachache. What is the most likely reason for Jack's upset stomach?
A. Soda and lactose from the cheese combined and slowed enzyme activity. B. Soda mixed with the pizza sauce and sped up digestive enzyme activity. C. Soda raised the pH in his stomach and sped up digestive enzyme activity. D. Soda lowered the pH in his stomach and slowed digestive enzyme activity.

Lab reagent, hypothesis test. a reference solution used as a lab reagent is purported to have a concentration of 5 mg/dl. six samples are taken from this solution and the following concentrations are recorded: (5.32, 4.88, 5.10, 4.73, 5.15, 4.75) mg/dl. these six measurements are assumed to be an srs of all possible measurements from solution. they are also assumed to have a standard deviation of 0.2, a normal distributin, and a mean concentration equal to the true concentration of the solution. carry out a significance test to determine whether these six measurements provide reliable evidence that the true concentration of the solution is actually not 5 mg/dl.