meaning of "falling-out"

[Rembo]

English Language Tests, Intermediate level

ESL/EFL Test #465 "English Slang Idioms (207)", question 9

"We are not on speaking terms at the moment. We had a .........-out over the decision of whether or not to put our parents in an old folks' home or to have them move in with one of us. My brother wanted to send them to a home and I didn't," Mark told Suzy.

(a) backing
(b) falling
(c) leaning
(d) bending

English Language Tests, Intermediate level

ESL/EFL Test #465 "English Slang Idioms (207)", answer 9

"We are not on speaking terms at the moment. We had a falling-out over the decision of whether or not to put our parents in an old folks' home or to have them move in with one of us. My brother wanted to send them to a home and I didn't," Mark told Suzy.

Correct answer: (b) falling

Your answer was: correct
_________________________

why falling?

Rembo

[Lost_Soul]

A falling-out means a row (British ), an argument.
When you and someone fall out, you're not on speaking terms anymore because you argued about something.