Which of the Following Is a True Statement

Which of the following is a true statement?

A) If the lethal dose of a psychoactive drug is high, we cannot reliably compute the drug's effective dose.
B) If the lethal dose of a psychoactive drug is low, we cannot reliably compute the drug's therapeutic ratio.
C) If the effective dose of a psychoactive drug is not established, we cannot reliably compute the drug's lethal dose.
D) If the lethal dose of a psychoactive drug is not established, we cannot reliably compute the drug's therapeutic ratio.