The technique used to teach animals complex tricks, such as teaching pigeons to play ping-pong, is:

this technique is a type of behaviour called " learning behaviour" that includes CONDITIONED REFLEX TYPE 1.

Explanation:

learning behaviour is a type which depends on the environmental influence, but the ability to modify the behaviour depends upon the heredity material.

for example:- in conditioned reflex type 1 the pigeons learn to play ping - pong. in this type of behaviour , the ability of learning depends upon the genetic basis of the individual.

sound moves fastest in solids because the molecules are tightly packed and it allows sound to vibrate