The correct option is A Liable
The word "liable" means responsible by law. For example, "the credit-card company is liable for any breach of contract". Hence, Option A is correct. Among the rest of the options, eligible means having the right to do or obtain something; satisfying the appropriate conditions, legalised means make (something that was previously illegal) permissible by law, legitimate means conforming to the law or to rules.These do not express the intended meaning, hence incorrect.