The correct answer is D.
The feature you should use to protect members of the Global Administrators group by making use of dynamic risk profiles is Microsoft Azure AD Conditional Access.
Option D, Microsoft Azure AD Conditional Access, allows you to create policies that use dynamic risk profiles to determine the level of access a user should have. With this feature, you can create policies that protect members of the Global Administrators group by requiring additional authentication factors or blocking access if the risk level is too high. Therefore, it is the correct answer.
Option C, Microsoft Azure AD Privileged Identity Protection, is a feature used to protect privileged accounts in Azure AD, but it does not make use of dynamic risk profiles, which is a requirement in the question. Therefore, it is not the correct answer.