Mark 'T' if the statement is true and 'F' if it is false:
Tooth decay is caused by the presence of a base. (T/F)

Answer

To determine whether the statement "Tooth decay is caused by the presence of a base" is true or false, we can analyze the causes of tooth decay step by step.

### Step-by-Step Solution:

1. **Understanding Tooth Decay**: Tooth decay is a dental condition that results in the destruction of tooth structure. It is commonly known as cavities or caries.

2. **Role of Bacteria**: The mouth contains various bacteria that feed on sugars present in food. When we consume sugary foods, these bacteria metabolize the sugars.

3. **Production of Acid**: As a result of this metabolism, the bacteria produce acidic compounds. These acids are harmful to our teeth.

4. **Effect on Tooth Enamel**: The acid produced by the bacteria can erode the enamel, which is the hard outer layer of the teeth. This erosion leads to the formation of plaque and eventually results in tooth decay.

5. **Conclusion**: Since tooth decay is caused by the presence of acid (not a base), the statement "Tooth decay is caused by the presence of a base" is false.

### Final Answer:
**F** (False)

---