Answer:
The head teacher asked me to come to school at ten 0'clock.
In my view all of the written above fits to definition of colloquial English. It's type of informal speech that applies idioms, slang etc. The one thing is not recommended in colloquial English is the usage of rude words. But it depends on region where you speak. There are differend idioms and slang in every region.
Answer:
The answer is a
Why?
Because you are supposed to replace "tastiest" with tastier.
