Which of the Following Would Indicate That the Lube Level

Which of the following would indicate that the lube level in a differential carrier housing was acceptable?

A) oil level is exactly even with the bottom of the filler hole
B) lube level pours out the filler hole when the plug is removed
C) lube level is one knuckle joint below the filler hole
D) lube level is within two knuckle joints below the filler hole