Introduction:
Controlling prices is an important objective of any economy to maintain stability and avoid inflationary or deflationary pressures. In the given options, the most effective method in controlling prices in the long run is an increase in production (Option B).

Explanation:
1. Relationship between production and prices:
- The level of production in an economy has a direct impact on prices. When production increases, the supply of goods and services in the market also increases.
- With an increase in supply, the overall availability of goods and services increases, leading to a decrease in prices.
- On the other hand, when production decreases, the supply of goods and services reduces, leading to an increase in prices due to scarcity.

2. Increase in production and its impact on prices:
- When production increases, the supply curve shifts to the right. This means that more goods and services are available at each price level.
- As a result, the equilibrium price level decreases due to the excess supply in the market.
- This decrease in prices benefits consumers as they can purchase goods and services at a lower cost, improving their standard of living.
- Additionally, lower prices also lead to an increase in consumer spending, which further stimulates economic growth.

3. Other options and their impact on prices:
- Decrease in production (Option A): This would have the opposite effect. It would lead to a decrease in supply, resulting in higher prices as scarcity sets in.
- Decrease in the rate of interest (Option C): Lower interest rates can stimulate borrowing and investment, leading to increased production. However, the impact on prices is not as direct as an increase in production.
- Increase in the rate of employment (Option D): Higher employment levels can contribute to increased production and economic activity. However, it does not directly control prices.

Conclusion:
In the long run, an increase in production is the most effective method of controlling prices. By increasing supply, it reduces scarcity, lowers prices, and benefits consumers. It also stimulates economic growth and encourages consumer spending, thus contributing to overall economic stability.

In my knowledge if u increse the production and its demand is low then how can it be successful?