serum creatinine115 ?

A 66-year-old woman was admitted with carpopedal spasm. During the previous week she had had 2 days of diarrhoea following treatment with ciprofloxacin for a urinary tract infection. She had long-standing rheumatoid arthritis treated with prednisolone 5 mg daily, and was also taking alendronic acid, omeprazole and furosemide.

Investigations:

serum creatinine115 ?mol/L (60C110)

serum corrected calcium1.79 mmol/L (2.20C2.60)

serum alkaline phosphatase124 U/L (45C105)

serum magnesium0.26 mmol/L (0.75C1.05)

plasma parathyroid hormone2.7 pmol/L (0.9C5.4)

Which medicine is most likely to be responsible for her metabolic derangement?
A . alendronic acid
B . ciprofloxacin
C . furosemide
D . omeprazole
E . prednisolone