Read the excerpt from "ship's chronometer from hms beagle.”

just as people adopted a common standard time, so numerous aspects of working and daily life were becoming rigidly fixed by the clock, from clocking on at work to school hours and tea-time – which is the subject of our next chapter.

what context clue best readers determine the meaning of the word standard?

“numerous”
“rigidly fixed”
“tea-time”
“subject”