Step 1: Identify policy.
The 'Policy of Isolation' aimed to protect tribal communities from outside influence, preserving their culture and traditional practices.
Step 2: Advocate.
Verrier Elwin, anthropologist and administrator, promoted this approach in India during the mid-20th century to ensure minimal disruption to tribal societies.
Step 3: Conclude.
\[
\boxed{\text{Verrier Elwin (Option D) advocated the Policy of Isolation.}}
\]