题干描述有相关方对项目有抵制，那么需要通过管理相关方参与过程，来提高他的支持，尽可能降低他的抵制。书PMBOK第六版P525:相关方参与计划是管理相关方参与过程的输入，为管理相关方期望提供指导和信息。

The correct answer is D: Investigate the rationale behind the stakeholder's objections. 调查相关方反对背后的理由。

**Professional Analysis:**

When dealing with opposition from stakeholders, especially regarding significant scope changes, it is crucial for the project manager to first understand the underlying reasons for the stakeholder's objections. This approach allows the project manager to gather essential information that can help in addressing the concerns effectively.

1. **Understanding Concerns:** By investigating the rationale behind the objections, the project manager can identify the specific issues or concerns that the stakeholder has. This understanding is critical for finding a resolution that addresses these concerns while still moving the project forward.

2. **Effective Communication:** Engaging with the stakeholder to understand their perspective fosters open communication and can lead to a more collaborative relationship. It shows respect for the stakeholder's position and a willingness to consider their input, which can be beneficial for future interactions.

3. **Informed Decision-Making:** With a clear understanding of the objections, the project manager can make more informed decisions about how to proceed. This might involve adjusting the scope change proposal, finding alternative solutions, or negotiating with the stakeholder to reach a compromise.

4. **Stakeholder Management:** Understanding objections is a key component of stakeholder management. It helps in maintaining a positive relationship with stakeholders and ensuring their support or at least minimizing their resistance, which is vital for project success.

In contrast, options A, B, and C involve taking action without first understanding the problem, which might lead to ineffective solutions or further complications. Therefore, the first and most logical step is to investigate and understand the stakeholder's objections.