This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharmacokinetics, Subject name: Pharmacology
Which is not true for therapeutic drug monitoring (TDM)? 
Select and explain. 
A. Done when clinical response can be easily measured, B. Done for narrow therapeutic index drugs, C. Digoxin is an example of a drug for which TDM is done, D. TDM can be done if drug has erratic pharmacokinetics
A: Done when clinical response can be easily measured
Answer: A: Done when clinical response can be easily measured 
Explanation: Criteria for doing TDM Low therapeutic index When therapeutic response cannot be easily measured Inconsistent pharmacokinetics of the drug TDM is done for A Aminoglycosides Drug Digoxin Possessing Phenytoin Very Valproate Low Lithium Therapeutic Tricyclic Antidepressants Index Immunosuppressants