The Kelvin–Planck statement of the second law says:

  1. no engine working in a cycle can convert all the heat it takes in into work
  2. energy is conserved
  3. entropy decreases
  4. heat flows from cold to hot
Answer

A) no engine working in a cycle can convert all the heat it takes in into work

Some heat must be rejected. SLO P-11-C-15 · Understanding

Physics MCQ · More Heat Engines, Second Law and Entropy MCQs · Practise