Concept:After the verb "claims", we use a "to"-infinitive to express what someone says happened.Explanation:The sentence talks about a past action: she says she saw someone jump."Claims" is followed by "to + base form" or "to have + past participle".Because the seeing happened before the claiming, the perfect infinitive "to have seen" is needed.The phrase then correctly becomes: "She claims to have seen someone jump over the fence."Answer:B. to have seen