Economical in Cost ?

If we have to choose mode which has low cost or if we have to choose mode which can send fast transmission rate over a long distance like given 2 miles? I am confused about question statement that it should economical in cost or can send data 2 miles?

Although Fiber Optics is considered as an expensive medium but still it provides you options for selecting a cheaper fiber type /mode or a costly type. In fiber optic, 2 miles is not considered as a long distance, so, you mainly have to focus on cost and have to select the cheaper one.