A Nurse Is Observing Another Nurse Prepare Insulin for Administration

A nurse is observing another nurse prepare insulin for administration to a diabetic patient.Which observation is considered unsafe?

A) The nurse draws up the Regular insulin first, then the NPH insulin.
B) The nurse draws up both the Regular and NPH insulin in the same syringe.
C) The nurse draws up the insulin in a syringe calibrated in milligrams (mg) .
D) The nurse draws up 30 units of NPH insulin as ordered by the physician.