What does 'do without' mean? Is it a phrasal verb and an idiom?

[Jenny]

Test No. incompl/inter-5 "do/make/get/take", question 8

As we don't have much money at the moment, we've decided to ......... without certain luxuries.

(a) do
(b) get
(c) make
(d) take

Test No. incompl/inter-5 "do/make/get/take", answer 8

As we don't have much money at the moment, we've decided to do without certain luxuries.

Correct answer: (a) do

Your answer was: correct
_________________________

Hello,
though i chose the correct answer, i dont undersand why it is correct answer.

Please expland for me.

[Torsten]

If you do without something you manage to live without it. To do without is a phrasal verb.

TOEFL listening lectures: Which of the following is true of biological indicators?