When Researchers Measure People's Psychological Characteristics,which of the Following Do

When researchers measure people's psychological characteristics,which of the following do they generally assume to be true?

A) Equal differences (intervals) between scores really do mean roughly equal differences in levels of the characteristic.
B) Equal ratios between scores really do mean roughly equal ratios in levels of the characteristic.
C) A score of zero really does mean a total absence of the characteristic.
D) When scores are ranked,equal differences between ranks really do mean roughly equal differences in levels of the characteristic.
E) All of the above.