[Vocabulary] regret or apologise?

[nado92]

[FONT=&quot]- We ......... to inform passengers that Flight 659 will be an hour late.[/FONT]​

[FONT=&quot] a) sorry
b) regret
c) disappointed
d) apologise

The given answer is '
[/FONT]​

[FONT=&quot] b) regret [/FONT]

But why cant we use apologise?
Thanks in advance.

 

[yuriya]

[FONT=&quot]- We ......... to inform passengers that Flight 659 will be an hour late.[/FONT]​

[FONT=&quot] a) sorry
b) regret
c) disappointed
d) apologise

The given answer is '
[/FONT]​

[FONT=&quot] b) regret [/FONT]

But why cant we use apologise?
Thanks in advance.

Usually, we deliver bad news
We regret to inform that . . .
We are sorry to inform that . . .

and then apologize.
We apologize for the delay.
We are sorry for the delay.