Difference between period and duration

[Guest]

Test No. incompl/advan-61 "Trains", question 2

We thought it was a good idea to take some sandwiches with us so that we'd have something to eat for the ......... of the journey.

(a) lasting
(b) period
(c) timing
(d) duration

Test No. incompl/advan-61 "Trains", answer 2

We thought it was a good idea to take some sandwiches with us so that we'd have something to eat for the duration of the journey.

Correct answer: (d) duration

Your answer was: incorrect
We thought it was a good idea to take some sandwiches with us so that we'd have something to eat for the period of the journey.
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please explain why it is the use of duration but not period. thank you. have a nice day.

[Alan]

Duration means the length of time something lasts: the duration of the flight - the duration of the war - the duration of the parliament. Period refers to a particular time in history/the past as in the classical period in music the romantic period in poetry.
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