What is the best way to say "Sorry, that I am writing so late"...?
a) Sorry, that I am writing so late.
b) I am sorry that write so late.
Or another variants.

Thank you in advance.

Question

What is the best way to say "Sorry, that I am writing so late"...?
a) Sorry, that I am writing so late.
b) I am sorry that write so late. 
Or another variants.

Thank you in advance.

Answer

I beg your pardon/sorry for my late writing

Answer

Sorry that I'm responding so late. (Informal context) 
I apologize for my late response. (More formal context)

Answer

I apologise for my delayed response
American spelling is apologize. I am Australian

Answer

Sorry for being late with my writing...