The question says structural limits .... ignore performance .... so we have 2 of them:
Maximum Zero Fuel Mass(MZFM) = Dry Operating Mass(DOM) + Traffic load(TL)
Maximum Structural Take Off Mass(MSTOM) = DOM + TL + Fuel
Short sector..... not much fuel, probably limited by MZFM
Long sector ... lots of fuel, probably limited by MSTOM
Of course in the real world we would consider MLM - always the 3 limits - MTOM, MZFM, MLM .... but in this question the word NORMALLY is the key.
In reality, not a very good question ….