**Core Concept**
The effectiveness of oral contraceptive pills (OCPs) can be influenced by various factors, including concomitant medications that may alter the pharmacokinetics of the estrogen and progesterone components. This can lead to reduced efficacy of the OCPs, resulting in contraceptive failure.

**Why the Correct Answer is Right**
Certain medications can induce the enzymes responsible for metabolizing the hormones in OCPs, such as CYP3A4 and CYP2C19. Rifampicin is a potent enzyme inducer that can significantly increase the metabolism of ethinyl estradiol and levonorgestrel, the active ingredients in many OCPs. This increased metabolism can lead to reduced plasma concentrations of these hormones, compromising the effectiveness of the OCPs and increasing the risk of contraceptive failure.

**Why Each Wrong Option is Incorrect**
**Option A:** Griseofulvin is an antifungal medication that can also induce liver enzymes, but its effect on OCP metabolism is less pronounced compared to rifampicin.
**Option B:** Anticonvulsants like phenobarbital and carbamazepine can also induce liver enzymes, but their effect on OCPs is generally less significant than that of rifampicin.
**Option C:** Tetracyclines are a class of antibiotics that can bind to calcium and magnesium ions, potentially affecting the absorption of OCPs, but this is not a significant concern with the majority of OCP formulations.

**Clinical Pearl / High-Yield Fact**
Rifampicin is a classic example of a medication that can lead to OCP failure due to its potent enzyme-inducing properties. This highlights the importance of careful patient counseling and monitoring when prescribing OCPs, especially in patients taking concomitant medications that may interact with the hormones.

**Correct Answer:** C.