**Core Concept**
Fluoride toxicity occurs when excessive fluoride intake exceeds the body's ability to excrete it, leading to cellular damage and ultimately, death. The lethal dose of fluoride varies depending on factors such as age, weight, and individual tolerance.

**Why the Correct Answer is Right**
The lethal dose of fluoride for a 70 kg adult is approximately 5-10 mg/kg, which translates to 350-700 mg for a 70 kg individual. This is equivalent to consuming a large quantity of fluoride-containing substances, such as rat poison or industrial-grade fluoride compounds. The mechanism of fluoride toxicity involves the inhibition of cellular enzymes, particularly enolase, which leads to a buildup of lactic acid and subsequent cellular damage.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the lethal dose of fluoride is not typically reported in milliliters (mL).
**Option B:** This option is incorrect because the lethal dose of fluoride is not typically reported in micrograms (μg) for a 70 kg adult.
**Option C:** This option is incorrect because the lethal dose of fluoride is not typically reported in grams (g) for a 70 kg adult.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the lethal dose of fluoride can vary depending on the individual's age, weight, and underlying medical conditions. Ingestion of fluoride-containing substances should be treated as a medical emergency, and prompt treatment is crucial to prevent serious complications.

**Correct Answer:** C. 350-700 mg