Matthew 22 and Mark 12 record the same 3 questions asked of Jesus. Luke 20 has the first 2 questions, but the 3rd one (Which is the greatest commandment?) is in Luke 10 and serves as the introduction to the Parable of the Good Samaritan.
The first question is about paying taxes to Caesar. The Pharisees get supporters of King Herod (who is king only because Caesar placed him there) to join them in asking this question. So it is obviously meant to trap Jesus, the supporters of Herod want a “yes” answer and the Pharisees want a “no” so it really isn’t a sincere question seeking an answer.
The next question is asked by the Sadducees, who deny that there is a resurrection. The question is about the resurrection, so it is also clearly not a sincere question seeking an answer.
Regarding the last question: What commandment is the greatest of all? Matthew states that the Pharisees are still testing Jesus, while the implication in Mark is that one of them might be sincerely asking the question. In any event, Jesus gives a direct answer, instead of the more indirect responses that he gives to the first two. In fact Jesus gives a bonus answer. Not only does he state that to love God with all your heart, and all your soul, and all your mind, and all your strength is the greatest commandment, but #2 is very similar, love your neighbor as yourself.
Since Jesus volunteers this additional answer, maybe our love for our neighbor should be somehow nearly as intently as our love for God; maybe love our neighbor not only in our religious life, but also our working (business) life, recreational time, and political positions as well as all other areas of our lives.