Answer:
C) We can always convert higher-order equations to a system of first-order equations.
This answer is self-explanatory: if higher-order equations can be made into a first-order equation, then, the need to learn how to solve higher-order equations could be considered unrquired.
However, this does not mean that people should not learn how to solve higher-order equations, especially those who are interested in pursuing a career in STEM subjects.
And students should also learn how to convert those equations in first place.