Decay of teeth is because of the sweetening agents we eat as it increases the acidity inside the mouth, which can be prevented if the toothpaste used is alkaline or basic in nature. Baking soda or sodium hydrogen carbonate is also used to clean the teeth as it is alkaline in nature.

The toothpaste which we use is basic in nature, so that it can neutralize the acid produced in mouth due to bacterial decomposition of sugary food inside mouth..Therefore , the correct answer is basic.

Toothpaste and Tooth Decay Prevention

Introduction
Tooth decay is a common dental problem caused by the accumulation of plaque on the teeth. It is essential to maintain good oral hygiene practices to prevent tooth decay. One of the most important recommendations is regular brushing of teeth using toothpaste. Toothpaste contains certain ingredients that help protect against tooth decay and maintain oral health.

The Nature of Toothpaste
The nature of toothpaste commonly used can be categorized based on its pH level, which indicates its acidity or basicity. The pH scale ranges from 0 to 14, with 7 being considered neutral.

Explanation of the Correct Answer
The correct answer is option 'C' - basic. Toothpaste is typically slightly basic or alkaline in nature. It is formulated this way to counteract the acidity produced by oral bacteria and help maintain a healthy pH level in the mouth.

The Role of Basic Toothpaste in Preventing Tooth Decay
1. Neutralizing Acids: When we consume food or drinks, especially those high in sugar or carbohydrates, oral bacteria break them down and produce acids as a byproduct. These acids can erode tooth enamel and lead to tooth decay. Basic toothpaste helps neutralize these acids, reducing their harmful effects on the teeth.

2. Remineralization: Toothpaste often contains fluoride, a mineral that helps strengthen tooth enamel and promote remineralization. Fluoride ions can replace lost minerals in the enamel, making it more resistant to acid attacks and preventing tooth decay.

3. Antibacterial Action: Some toothpaste formulations include antibacterial agents, such as triclosan or zinc citrate, which help inhibit the growth of oral bacteria. By reducing the bacterial population in the mouth, toothpaste can help prevent the formation of plaque and the subsequent tooth decay.

4. Mechanical Cleaning: Toothpaste contains mild abrasives that aid in the mechanical cleaning of teeth. These abrasives help remove plaque, food particles, and surface stains from the teeth, ensuring better oral hygiene and reducing the risk of tooth decay.

Conclusion
Toothpaste, being slightly basic in nature, plays a crucial role in preventing tooth decay. It neutralizes acids, promotes remineralization, has antibacterial properties, and aids in mechanical cleaning. Regular brushing with toothpaste, combined with other oral hygiene practices like flossing and regular dental check-ups, can significantly contribute to maintaining good oral health and preventing tooth decay.