Co-efficient of adhesion is________________-?

A. high in case of D.C. traction than in the case of AC. traction
B. low in case of D.C. traction than in the case of AC. traction
C. equal in both AC. and D.C. traction
D. any of the above

A permanent magnet______________?

A. attracts some substances and repels others
B. attracts all paramagnetic substances and repels others
C. attracts only ferromagnetic substances
D. attracts ferromagnetic substances and repels all others