Answer:
Step-by-step explanation:
Normally, running underground distribution line is expensive to run and also to maintain(repair) though running it underground makes it last longer by keeping it safe away from things like ice.
Just like it is given in the Question/problem above that "laying the distribution lines cost twice as much under water as it does on land". It can be observed that the cost of taking the distribution line under water is higher than it does on the land. So, in order to minimize cost the following should be done;
=> Major part of the distribution line should be done on the land and drawn along the side of the water body. The minor part of the distribution line can then go down(under the water).