Pavlov noted that his experimental dogs began to salivate when they heard the footsteps of the attendants who brought them food. this led to his research in:

Classical conditioning

Explanation:

the answer is c most of the fortnite players usually buy v bucks to get the battle pass and other cosmetics but some players who are referred to as "no skins" don't   buy skins and are usually noobs.

read more on -

the dna molecules have a negative charge because of the phosphate groups in their sugar-phosphate backbone, so they start moving through the matrix of the gel towards the positive pole. power is turned on and dna fragments migrate through gel (towards the positive electrode).

explanation: