A 75-year-old man had been receiving gentamicin (an aminoglycoside antibiotic) to treat an urinary tract infection. After three months of therapy patient's serum creatinine levels were 10 mg/dL ( normal 0.5-1.2) and serum gentamicin concentrations obtained just before the last dose were 9 mg/dL (normal < 2). Which of the following is the most likely adverse drug reaction the patient was suffering from? a) Type II allergic reaction b)Type III allergic reaction c) Pseudo allergic reaction d) Overdose toxicity