Leonardo da Vinci was well known for bringing proper anatomy into the landscape of art. He had painstakingly perfected human anatomy through somewhat gruesome studies. The artist performed more than 10 human dissections in attribution to his work, becoming familiar with proportions and how the body should be drawn. From his findings, other artists were able to study his published notes and works for reference.
Best of luck! :)
A. banks and tax officers and C. business heads and maybe E. We might need some lawyers.