The high school principal who is very supportive of the local chapter should join HOSA-Future Health Professionals in the Secondary membership category.
Why should he join Secondary membership category?
This category is specifically designed for high school students, advisors and administrators who want to be part of HOSA at the secondary school level. Principals fall under the category of administrators and their active participation in the "Secondary" category can provide valuable support and guidance to the local HOSA chapter.
This membership allows them to actively engage with students interested in healthcare careers, offer mentorship and contribute to the growth and success of the organization within their high school.
Therefore, the Option C is correct.