To check the lifetime of a new battery in a soon‑to‑be‑released smart watch with GPS, an engineer used the GPS‑tracking feature of the watch continuously, beginning with a fully charged battery, until the battery was drained. The engineer repeated this for a total of 10 times. He compared the results with the lifetime of 4.8 hours for the current battery used in the company's GPS‑enabled smart watch. The described situation involves inference about a mean or means which involves:

a. two independent samples.

b. a single sample.

c. a matched pairs design.

d. none of the choices.