Explanation
The dependency between software installation and desktop installation is a mandatory dependency. A mandatory dependency is a type of dependency that is inherent in the nature or logic of the work and cannot be avoided or changed. It is also known as a hard dependency or a hard logic dependency. A mandatory dependency means that one task must be completed before another task can start or finish. For example, software installation can only start after desktop installation is finished5 The dependency between desktop installation and software installation represents a mandatory dependency. A mandatory dependency is a type of task dependency that is inherent in the nature of the work being performed.
In this case, software installation cannot begin until desktops are installed and powered on, and therefore, the dependency is mandatory. References: CompTIA Project+ Study Guide, Chapter 3: Project Integration Management, Objective 3.1: Identify the project management processes and the interactions between them.

The project sponsor is the person who provides the authority, funding, and support for the project. The project sponsor can also help to influence and engage the key stakeholders who are essential for the success of the project. If several stakeholders have declined the invitation for the kickoff meeting, which is an important event to establish the vision, scope, and expectations of the project, the project manager should escalate this issue to the project sponsor and seek their assistance to ensure the participation of the stakeholders1, p. 47

Incorrect configuration was the initial cause of the issue that caused the unexpected crash of the website that the team was developing. The diagram given is an example of a fishbone diagram or a cause-and-effect diagram that shows the possible causes of a problem or effect. The diagram has four main categories: people, process, technology, and environment. Each category has subcategories that list specific factors that may contribute to the problem or effect. The diagram shows that incorrect configuration under technology was marked as an initial cause of website crash.

The percentage of risk investments with defined business cases is a metric that measures how well the information security program aligns with the operational objectives of the organization. It indicates how many of the security-related investments are justified by a clear analysis of the expected benefits, costs, and risks, and how they support the business goals and priorities. This metric can help the organization optimize its security spending, demonstrate the value of security to the stakeholders, and align the security strategy with the business strategy1. Reference = Performance Measurement Guide for Information Security, Section 3.2.3, page 16; Key Performance Indicators for Security Governance, Part 1, Section 3, page 3.

Milestones are activities with zero duration that are added to a project schedule by a project manager.
Milestones are significant events or achievements in a project that mark the completion of a phase, deliverable, or task. Milestones can help to track and measure the progress and performance of a project and communicate it to stakeholders.