"That's no reason." or "That's no excuse."

-Look，the boss is very angry with Alex．

-Well，he came late again．But that's no______ to shout at him．

A. excuse

B. reason

Our teacher told us that the answer was B.

There’s no further context for this question.

I chose excuse and I think That’s no excuse... conveys almost the same meaning as That’s no reason....

What's your opinion?

It is important to consider not only the phrase but where it is used, so while the phrases convey a similar message they do not necessarily fit equally well into any one sentence structure.

For example, I would use the two phrases like this:

... reason to shout at him.

... excuse for shouting at him.

.... excuse why he should shout at him.

The danger with this kind of question is that usage can vary geographically and with the kind of people using the phrases, and teachers are always at risk of refining the language too far.