Which of the following is the most polar?

Which of the following is most polar ?

Which of the following is most polar?

Which of the following is most polar bond ?

Which of the following is most polar bond ?

Which of the following is least polar ?

Which of the following bonds is most polar ?

Which of the following bonds is most polar ?

The electronegativity values of C, H, O, N and S are 2.5, 2.1, 3.5, 3.0 and 2.5 respectively. Which of the following bonds is most polar?