What does get his point across mean?

[Pasban110]

English Language Tests, Intermediate level

ESL/EFL Test #256 "Irregular Verbs Test (4)", question 5

David ......... increasingly upset because he couldn't get his point across.

(a) become
(b) became
(c) becoming

English Language Tests, Intermediate level

ESL/EFL Test #256 "Irregular Verbs Test (4)", answer 5

David became increasingly upset because he couldn't get his point across.

Correct answer: (b) became
_________________________

What does get his point across mean?

[Mister Micawber]

Successfully communicate his idea or opinion.
_________________
Native English teacher at Mister Micawber's

[Grasi02]

to get someone's point across means
to say the right words as you exactly mean it.
Somehow you want to be careful that it will not be misunderstood.
It means the interpretation of the listener should be correct.

David was upset because he couldn't get his point across...
maybe he runs out of words and couldn't explain
OR he feels that he was not understood by his audience/listener

If you're a man proposing to a woman for marriage and you get tongue-tied because you are nervous, then like David you won't be able to get your point across.