Here is what the argument tells us Tooten County has fewer young families (fewer families with young children) than other counties. Even so, they manage to sell more children's cycles than the other cities.

What could be the reason here? They don't have many children in their County, yet their bicycle sales are very high. So bicycle sales must not be restricted to Tooten alone, they must be selling the bicycles to other counties too.

Option A tells us this. The biggest retailers market their bicycles to the neighboring counties. So children from neighboring counties and children from Tooten are buying their bicycles.

Option B doesn't help reconcile the paradox at all.

Option C would have been an excellent choice had they said Tooten County exported to Canada. But they import bicycles. This doesn't help us explain why their sales are higher than the national average.

Option D doesn't say anything about elementary schools in other counties. Suppose they too are promoting values of exercise?

Option E confuses us even more. It brings in extra information about renting bicycles when we want to know about bicycle sales. Unnecessary. Ignore.

Hope this helps!