This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Digoxin toxicity is aggravated by: a) Hypokalemia b) Hyperkalernia c) Hypercalcemia d) Hypermagnesemia e) Hypocalcemia 
Select and explain. 
A. ad, B. bc, C. cd, D. ac
D: ac
Answer: D: ac 
Explanation: None