**Core Concept**
First-order kinetics is a pharmacokinetic process where the rate of drug elimination is directly proportional to the drug's plasma concentration. After a certain period, the drug's plasma concentration decreases exponentially, and the rate of elimination remains constant.

**Why the Correct Answer is Right**
The correct answer is based on the concept of half-life (t1/2). After one half-life cycle, 50% of the drug is eliminated, leaving 50% behind. After two cycles, 75% is eliminated, after three cycles, 87.5% is eliminated, and after four cycles, approximately 93.75% of the drug is eliminated. This is because each half-life cycle reduces the remaining drug concentration by 50%, resulting in an exponential decrease.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it doesn't follow the exponential decrease in drug concentration after each half-life cycle.
**Option B:** This option is incorrect because it doesn't accurately represent the percentage of drug eliminated after four half-life cycles.
**Option C:** This option is incorrect because it doesn't account for the cumulative effect of four half-life cycles on the drug's plasma concentration.

**Clinical Pearl / High-Yield Fact**
Remember that first-order kinetics is characterized by an exponential decrease in drug concentration, resulting in a predictable and consistent rate of elimination.

**Correct Answer: C. 93.75%**