This question if for you girls who needs points

               

Answer(a) one needs to learn from experts and be determined to be the best in the field;

What exactly are you asking? i’d love to , explain, what you are asking : )

Some connecting rods have to lubricate the cylinder wall or piston pin. the answer is letter d. graphite coating can be a major  additive to many  coating  systems and things such as connecting rods.  it functions as a refractory, lubricant, thermal conductor, and electrical conductor for a machine or thing to enhance its work.