Which sentences are OK?

Person A - When will you get home?
Person B - Why are you asking?
Person A - I'm locked out.
Person B - I'll be there in about 30 minutes.

If Person A replies following sentences;
OK, l'll be waiting for you out front.
OK, l'll be waiting for you at the door.
OK, l'll be waiting for you in the doorway.
OK, l'll be waiting for you at the doorway.

Question

Which sentences are  OK?

Person A - When will you get home?
Person B - Why are you asking?
Person A - I'm locked out.
Person B - I'll be there in about 30 minutes.

If Person  A replies following sentences;
  OK, l'll be waiting for you out front.
  OK, l'll be waiting for you at the door.
  OK, l'll be waiting for you in the doorway. 
  OK, l'll be waiting for you at the doorway.

Answer

They are all grammatically correct, but sentences one and two sound more natural.

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