Answer:
A Is false, because that'd be 300.
B Is correct, because 9 rounded to the nearest is 10, plus the 300 original.
C I don't know what a unit is, but if it's ones value, then that's incorrect. It'd be 310.
D Incorrect, you can't round and have ".8"
E. Incorrect, can't round and have any decimal numbers...
Explanation: