According to the Harvard Research Project, the three primary and interrelated factors critical to achieving youth outcomes are 

A. beginning on time, daily interaction, and strict discipline. B. enjoyable transitions, friendly parent-teacher relations, and imaginative stories. C. planning, relevance, and structure. D. access to and sustained participation, high-quality curriculum, and strong partnerships. 

D.

To determine the correct answer to this question, you need to identify the primary and interrelated factors critical to achieving youth outcomes according to the Harvard Research Project.

1. Begin by conducting a search using the keywords "Harvard Research Project youth outcomes" to find information about the project and its findings.
2. Look for credible sources such as academic articles, research papers, or publications from the Harvard Research Project itself.
3. Review the information and findings from these sources to identify the three primary and interrelated factors that are deemed critical to achieving youth outcomes according to the project.

In this case, after conducting the research described above, you will find that the correct answer is D. Access to and sustained participation, high-quality curriculum, and strong partnerships are the three primary and interrelated factors critical to achieving youth outcomes according to the Harvard Research Project.