30,000, because if you look in the 6 in the thousands place it is over 5 so you round up
"briefly" is the adverb: it gives the information about how some action was performed, and adverbs modify verbs to give some information about how the action is performed.
Also, -ly is a typical adverb ending.
589, 310
The 8 value is in the 10,000s place.
598, 301
The 8 is in the 1000s place.
So the difference of 10,000 over 1000 is 10
So your answer is B