In the context of factors of production, suppliers are powerful when:

• A. the inputs are widely available and standardized
• B. the demand for the inputs is low
• C. buyers have many alternative sources for the inputs
• D. there are few substitutes for the inputs they provide

Answer: (D)

Verified step by step guidance

1. Understand the concept of supplier power in microeconomics, which refers to the ability of suppliers to influence the price and terms of supply for inputs (factors of production).
2. Recognize that supplier power increases when suppliers provide inputs that are essential and have few or no substitutes, making it difficult for buyers to switch to alternative sources.
3. Analyze the conditions given: if inputs are widely available and standardized, supplier power tends to be low because buyers can easily switch suppliers.
4. Consider that low demand for inputs also reduces supplier power since suppliers have less leverage over buyers.
5. Conclude that supplier power is strongest when there are few substitutes for the inputs they provide, as this limits buyers' options and increases suppliers' influence.