Step 1: Understanding the Concept:
"Tooth and nail" is an idiom meaning fighting very fiercely, using all one's physical strength and determination.
Step 2: Detailed Explanation:
The idiom suggests a savage, intense struggle. "With weapons" is too literal. "As best as he could" lacks intensity. "Using unfair means" implies dishonesty. "With strength and fury" captures the fierce, determined nature of the idiom.
Step 3: Final Answer:
Thus, "with strength and fury" best expresses the meaning.