What does mortgage and pre-approved mean?

[Kotow]

English Language Tests, Intermediate level

ESL/EFL Test #232 "Bank Terminology (2)", question 9

Rose and Tom want to get approved for a ......... because they want to buy a house this year.

(a) check
(b) safety deposit box
(c) mortgage
(d) savings account

English Language Tests, Intermediate level

ESL/EFL Test #232 "Bank Terminology (2)", answer 9

Rose and Tom want to get approved for a mortgage because they want to buy a house this year.

Correct answer: (c) mortgage

Your answer was: correct
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What does mortgage and pre-approved mean?
Thanks
Kotow

[Mister Micawber]

Don't you have a DICTIONARY?
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Native English teacher at Mister Micawber's