The phase of internalization whereby children do something to gain rewards, or because someone made them, is the phase.

The answer to this question is "Psychosocial Stage", hence to complete the statement we have "The phase of internalization whereby children do something to gain rewards, or because someone made them, is the Psychosocial stage". This focus on orientation between self and others.

Diamond producer restrict diamond quantity supply to certain limit in market

Explanation:

Diamond is a precious gem stone that used for making jewelry pieces and other related items.It is also used for making diamond ring but there is scarcity of it in market as it is an expensive thing and many people are ready for paying lot of amount for it .Thus, producer of diamond limit its supply quantity in market

Other options are incorrect because diamonds are not less common in market than other gems, demand is not extensively high in market and neither it faces monopolistic competition.