Concept:First remove the birds that were sold, then share the remaining birds equally among the cages (division).Given:Total birds = 150, sold = 26, cages = 4.Solution:Birds remaining =150−26=124Birds in each cage =124÷4=31Check: 31×4=124 and 124+26=150 ✓.Key point: Dividing 150 by 4 before subtracting the sold birds gives a wrong result; the sold birds are not in the cages.Answer:Option C (31)