Which of the Following Best Describes the Technical Challenge That

Which of the following best describes the technical challenge that prevents fusion from being utilized to produce energy?

A) It is difficult to sustain and control the high temperatures need for fusion.
B) The fuels that readily undergo fusion are rarer than uranium and need substantial amounts of enrichment.
C) The byproducts of the nuclear reaction are extremely radioactive and have long half lives, making them difficult to dispose of.
D) By mass, less energy is produced in fusion reactions than in fission reactions.
E) None of the above