the = definite article

a/an = indefinite article

For example, if I say, “Let’s read the book,” I mean a specific book. If I say, “Let’s read a book,” I mean any book rather than a specific book.

Here’s another way to explain it: The is used to refer to a specific or particular member of a group. For example, “I just saw the most popular movie of the year.” There are many movies, but only one particular movie is the most popular. Therefore, we use the.

“A/an” is used to refer to a non-specific or non-particular member of the group. For example, “I would like to go see a movie.” Here, we’re not talking about a specific movie. We’re talking about any movie. There are many movies, and I want to see any movie. I don’t have a specific one in mind.

– or she should have used instead “I apologize for my answer to the earlier question” if maybe the question is more specific.. in case if its too broad or unspecific she used “an”

for it