I think I'm getting it. There are two questions: the importer who goes to the bank = the importer that goes to the bank to establish a line of credit = to establish an lc If you choose the acronym lc for line of credit, then you say "lc". Not only is it true that (most) vowels beginning words are preceded by "an" rather than "a", but some letters are too. Let me go through them all in my mind: f h l m n r s x (I didn't include a, e, I or o - since they are too obvious) Why? Because if you imagine, for example, the letter "s" spelled out it would be "ess"; let's try another ---- x -----"ex" Note that because we pronounce the vowel "u" "you" it doesn't need the "n" after "a". It's a u. So "lc" is an "ell see" if you wanted to write it out. Note that ell see doesn't mean anything. I just wrote it out to show how it is pronounced. Did you understand that? Hoping that your difficulty will last shorter than your chronic prostatitis.

The choice of "a" versus "an" is based on sound, not spelling. I'm not sure what L/C stands for, but when letters are used like this, they are usually pronounced by naming letters: "El-see." Since the name of the letter L begins with a vowel sound, we use "an" in front of it. "In order to spell 'italki,' I need to us an 'i,' a 't,' an 'a,' an 'l,' a 'k,' and an 'i.'"

I know you've chosen the answer, but I wanted to also comment on the 'that/who' question: In this case, the writer probably chose 'that' because 'the importer' is not a person but a corporation or other commercial entity. Thus, using 'that' is used to depersonalise "the importer".

Who sounds more formal/politer but 'that' is perfectly acceptable. We all use who/that interchangeably. And 'A' is much easier to say than 'AN' in front of many words. Basically, we say whatever is easiest to say.

what does the first question have to do with the second? I guess an L/C is a line of credit; is that right?