Here, we have to find an answer which is actually not an assumption. Why?
Because, if we see the question stem, it uses a word "EXCEPT".
So, what we have got here are 5 assumptions out of which 1 does not help us to fill the gap between the conclusion and the premises.
Analyzing the options here,
A. This is a valid assumption. Why? Because if the demand for electricity does not increase, then there won't be any increase in the profit. So, it is required that the demand for electricity increase.
WrongB. This is a valid assumption. Why? Because if the expenses rise above the level that could be compensated by the efficiency or volume of operation, or both, then the profit that is obtained will go down. So, we have to assume that the expenses does not rise above a certain level.
Wrong C. This is a valid assumption. Why? Because this option talks about adding more benefits to the company as a whole and that should be a valid assumption.
WrongD. This is not a valid assumption. We are really concerned about the profit that we can get from the new plant. So, we don't actually need to assume anything about the safety measures. Since we are looking for an option which is not an assumption that is required, this option is the correct answer.
Correct E. This is a valid assumption. Why? because if tripling the capacity would take a toll on the efficiency, then we cannot increase the profit. So, it is required that no issue affects the efficiency of the plant.
Wrong _________________