The correct option is A 2800
Given number is 2784.
2784 lies between 2700 and 2800
The number formed by last two digits of 2784 is 84.
If the last two digits form a number greater than or equal to 50, then the given number is rounded off to the nearest multiple of 100 which is greater than the number.
∵ 84 > 50.
∴ 2784 is rounded off as 2800.