When both partners/components are affected negatively, the nature of the interaction is

Options

A. Commensalism
B. Predation
C. Competition
D. Amensalism

Explanation

To determine the nature of interaction when both partners or components are negatively affected, we can analyze the options provided:

1. **Commensalism**: In this interaction, one organism benefits while the other is neither helped nor harmed. Therefore, this does not fit our criteria since both partners are not negatively affected.

2. **Predation**: In predation, one organism (the predator) benefits by consuming another organism (the prey), which is negatively affected. This means that in predation, only one partner is negatively affected, so this option is also not suitable.

3. **Competition**: This interaction occurs when two organisms strive for the same resources (like food, space, or light). In this case, both organisms are negatively affected because they are competing for limited resources, which can lead to reduced availability for both. Thus, competition fits the criteria where both partners are negatively affected.

4. **Amensalism**: In this interaction, one organism is harmed while the other is unaffected. This means that again, only one partner is negatively affected, making this option incorrect.

Based on the analysis, the correct answer is **competition**.

### Step-by-step Solution:
1. **Identify the options**: Look at the types of interactions provided: commensalism, predation, competition, and amensalism.
2. **Analyze each option**:
- Commensalism: One benefits, the other is unaffected.
- Predation: One benefits, the other is harmed.
- Competition: Both strive for the same resources, leading to negative effects on both.
- Amensalism: One is harmed, the other is unaffected.
3. **Determine the correct interaction**: Since competition is the only interaction where both partners are negatively affected, we conclude that the answer is competition.