Two errors sit in the underlined part. "Besides from" is not standard English; the correct phrase is either "besides" alone or "apart from", never both combined. Also "Office Ergonomics" is a single subject, a field of study, so it needs the singular verb "is", not the plural "are".
Option B is the only choice that fixes both the phrase and the verb agreement, so it is correct.
If the price of a commodity increases by 25%, by what percentage should the consumption be reduced to keep the expenditure the same?