You are distributing vegetable oil

You are distributing vegetable oil. there are 21 bottles in total out of which 7 are full, 7 half empty, 7 empty. the oil has to be distributed among three people. how will you distribute so that each person gets equal number of bottles and the same quantity of oil

Its source gives only the correct option, without the working.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #96648