the correct answer is a compound since heterogeneous means multiple of the same different elements and substance isnt accurate and homogeneous means same. so the correct answer is a
a) time for salt to dissolve.
this factor depends on the other steps mentioned to dissolve the salt.
try this solution:
if 1 mole is 55.8 gr., then 2.25 moles the mass should be 55.8*2.25=125.55 gr.
answer: 125.55 gr.