Meaning of 'joint account'

[Jon]

Test No. incompl/advan-54 "Taxes", question 3

The arrangement they have is that all the money that has to be paid in tax out of their earnings comes from their ......... account.

(a) joined
(b) conjoined
(c) joined up
(d) joint

Test No. incompl/advan-54 "Taxes", answer 3

The arrangement they have is that all the money that has to be paid in tax out of their earnings comes from their joint account.

Correct answer: (d) joint

Your answer was: n/a
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Hi,can you please tell me what's the meaning of joint here.I was confused.Many thanks!!

[Alan]

A joint account is a shared account for two people.
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