The __________ the LD50 number, the more toxic the product.

The __________ the LD50 number, the more toxic the product.

• A. Larger
• B. Higher
• C. Smaller
• D. Lower

Answer: (C)

The key idea is that toxicity rises as the needed lethal dose drops. LD50 is the amount that kills 50% of a test population. If only a small amount causes death, the substance is highly toxic; if you need a larger amount, it’s less toxic. So the phrase that fits is smaller—the smaller the LD50, the more toxic the product. A larger or higher LD50 would mean you need more of the chemical to reach the same effect, indicating lower acute toxicity. The option chosen reflects this inverse relationship.

The key idea is that toxicity rises as the needed lethal dose drops. LD50 is the amount that kills 50% of a test population. If only a small amount causes death, the substance is highly toxic; if you need a larger amount, it’s less toxic. So the phrase that fits is smaller—the smaller the LD50, the more toxic the product. A larger or higher LD50 would mean you need more of the chemical to reach the same effect, indicating lower acute toxicity. The option chosen reflects this inverse relationship.