Concept:The subject is “One” (singular), so the verb must be singular and active.Explanation:The phrase “of the cows” is a prepositional phrase and does not change the subject.The singular subject “One” takes “has”, not “have”.“Strayed” is an action the cow does itself, not something done to it, so the passive “been strayed” is incorrect.Thus the correct choice is “has strayed”.Answer:A. has strayed