Adding to his frustration was the fact that very few official papers had made their way to him at Mount Vernon. Washington was a stickler for orderly files that he could search at a moment's notice. This was the most important way he kept himself informed about the hundreds of things happening in the fledgling nation. Unfortunately, when the government clerks had panicked and dashed from Philadelphia, they had abandoned all papers and records in boarded-up houses.

Which line from the passage can be defined as the cause?

"Adding to his frustration was the fact that very few official papers had made their way to him at Mount Vernon."
"Washington was a stickler for orderly files that he could search at a moment's notice."
"This was the most important way he kept himself informed about the hundreds of things happening in the fledgling nation."
"Unfortunately, when the government clerks had panicked and dashed from Philadelphia, they had abandoned all papers and records in boarded-up houses."