How many IOPS can ChildSG3 expect to achieve?

A parent SG has three child SGs; ChildSG1, ChildSG2, and ChildSG3. The parent SG has a Host I/O Limit of 1000. The child SGs have I/O Limits of 500 each. ChildSG1 and ChildSG2 are both sustaining I/O rates of 300 IOPS.

How many IOPS can ChildSG3 expect to achieve?
A . 400
B . 500
C . 900
D . 1000

Answer: A