单选题
[填句补文]In order to produce high quality products， the Tasmanian government understands the need for getting high quality irrigation equipment at all times， such as travelling irrigators（灌溉车）， pumps and other irrigation tools， which are the key to the success of the growers. It is also no wonder why irrigation equipment makers and suppliers are making much money in the region. ______
A.They play a key role in meeting the needs of the farmers.
B.Through the years， people there have come up with long-term solutions that mainly focus on developing or improving its various irrigation systems.
C.Travelling irrigators first appeared in the East Han Dynasty in China.
D.Next on the list is drip irrigation and spray irrigation.
正确答案：A
答案解析：答案选A。此句与上句间具有轻微的因果关系，基本解释也是总结了上句讲到了灌溉设备的制作方和零售商赚钱的原因和意义。