A Patient Is Weighed in the Hospital by a Nurse,and

A patient is weighed in the hospital by a nurse,and she is told she weighs 170 pounds.The next morning she weighs herself at home,and her weight is 168 pounds.Assuming that both scales were calibrated and the patient was measured under the same circumstances (no shoes,light clothing) .What can explain the difference in weight?

A) Intrasubject variability
B) Intersubject variability
C) Intraobserver variability
D) Low specificity of the test
E) Low sensitivity of the test