政策性农业保险是以保险公司为依托，政府通过保费补贴扶持，对种植业、养殖业因遭受自然灾害和意外事故造成的经济损失提供的保险。该保险的实施有利于

A．降低农业成本，提高农业经济效益

B．发挥财政作用，优化农村产业结构

C．完善社会保障，促进收入分配公平

D．分散生产风险，切实保护农民利益

Realizing the boy was too poor to pay for the book, the shopkeeper of the bookstore gave him the book _____. [ ]

A. off free

B. with free

C. for freely

D. for free