Question

which piece of text uses this meaning of certain?
certain adjective free from doubt
\are you absolutely certain that this is the most direct route to the airport?\ ms. weber asked the taxi driver. \im running a bit late.\
martina smith, the newest addition to our acting troupe, has a certain something that audiences love.

Explanation:

The target meaning of "certain" is "free from doubt". In the first text, Ms. Weber asks if the taxi driver is absolutely free from doubt about the route matching this definition. The second text uses "certain" to mean a particular, intangible quality, not "free from doubt".

Answer:

"Are you absolutely certain that this is the most direct route to the airport?" Ms. Weber asked the taxi driver. "I'm running a bit late."