Step 1: Understanding the Concept:
Farm biosecurity and bovine claw hygiene: liquid walk-through footbaths utilize formalin and copper sulfate, while dry footbaths and farm entry pits routinely use slaked/unslaked lime.
Step 2: Detailed Explanation:
1. Statement I: In dairy herd lameness prevention (controlling contagious digital dermatitis and foot rot), the standard chemical solutions used in walk-through liquid foot baths are Formalin ($3\% - 5\%$) and Copper Sulphate ($5\% - 10\%$). Hence, Statement I is correct.
2. Statement II: Lime (Quicklime Hydrated Slaked Lime, $\text{Ca(OH)_2$)} is widely and standardly used in livestock operations as a dry foot bath powder or mixed into entryway disinfectant foot dips to dry hooves and provide alkaline disinfection against foot rot. Claiming that lime is 'not used' is false. Hence, Statement II is false.
Step 3: Final Answer:
Thus, Statement I is correct but Statement II is false, matching option (C).