Answer: E
Correct answer: have arrested
Police is a plural noun in English and always takes a plural verb: the police have arrested. It has no singular form - one refers to a policeman, a police officer or a member of the police. A small group of nouns is plural in form or sense despite looking singular, and each is a standard examination point: police, cattle, people, vermin, poultry and gentry all take plural verbs. The mirror-image group looks plural but is singular: news, mathematics, physics, economics, politics, innings and measles. So the news is good and mathematics is difficult. A third group is always plural and needs a pair of to be counted: scissors, trousers, spectacles, tongs and pliers.