Going to go out?

English as a Second Language English Vocabulary, Grammar and Idioms
1

What is grammatically incorrect with the following sentence?
What time are you two going to go out? Choose one answer.
a. It ends with a preposition.
b. The phrasal verb “go out” is casual English and as such, it should only be used in speech, never in writing.
c. There is nothing grammatically wrong with this sentence.
d. The infinitive “to go” should be split by an adverb.

I think the answer is c? I appreciate your help.

2

I agree with you.
WW

3

Thank you Walt Whitman. I appreciate it.

4

Some teachers say, we simply use going and coming instead of going to go and going to come. Since it is more natural.

kind regards.