Answer: 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.
