Many dog owners tend to think that dog training_____.

　　细节理解题。

　　定位到文中第七段的第三段和第四段，“One major mistake many dog owners make it to think that the dog training is over. Training your dog continues throughout your dog's life.”，许多狗的主人犯的一个主要错误是认为训狗花费时间短，很快就结束了，而实际上狗在一生中都要接受训练。故选C。