Read the following​ sentence, and then select the group of words that consists of only nouns.​Instead, he believed humans should turn their efforts to providing conditions that reinforce desired​ behavior, thus improving human behavior in​ general.A.humans, efforts,​ behavior, thusB.​he, efforts,​ providing, conditionsC.​Instead, humans,​ behavior, generalD.​humans, efforts,​ conditions, general