The scientific community's initial _____ to the groundbreaking theory was one of cautious _____, as its proponents lacked the empirical data needed to _____ its claims definitively.

✓ Correct Answer: Option D

The first blank describes how the theory was met ('reception'). 'Cautious scrutiny' indicates careful examination with reservations. The lack of empirical data suggests they needed to 'validate' or prove its claims.