Town Mission 18: The Test of Heart

The Test of Heart is Silver's 18th mission Sonic 06. The objective is to destroy all enemies within a certain are without the use of any object nearby (for example: Boxes).

Guide
To gain the S-Rank, it is important to destroy the leader Gold Rhino and the leader White Hornets to gain extra bonus points.

Source
http://www.gamefaqs.com/ps3/929718-sonic-the-hedgehog/faqs/46072