In the next decade, a large percentage of municipalities throughout the country will experience power failures if they do not modernize their electrical substations. The vast majority of substations in the country already handle currents between 60% and 80% of their maximum capacity, and currents are expected to rise, perhaps by as much as a factor of 3 in the next decade, because of population increase and the increased demand from both industry and electronics in individual homes.

Which of the following is an assumption of the above argument?

A:An electrical substation fails when the current it handles rises above its maximum capacity.

B:A modernized electric substation would be able to handle at least three times the amount of current as does a current substation.

C:Ten years from now, the average household will own a greater number of electronic devices than does the average household today.

D:Many electrical substations in operation today are old, and have several aged components that could break down, leading to power failures, even if current levels don't increase substantially.

E:The cost of modernizing the substations is small compared to the average profits of electrical power companies.