Choose all answers that are correct. a)the fourth estate was made up of "commoners." b)it was very difficult to change membership in an estate c)this social structure made most french people happy. d)french aristocrats belonged to the second estate. asap

B and D are correct. 
A is incorrect because there were only three estates. The third estate was made up of peasants (farmers) and the bourgeoisie (working class). The second estate was made of aristocrats and nobility. The first estate was the Church.  

C is incorrect because approximately 98% of the French population were in the Third Estate and they very unhappy with being forced to pay the majority of the taxes to the king. 

B is correct because very rarely could someone move up an estate. Occasionally peasants would become bourgeois but considering how nobility married within nobility it was highly unlikely that they would marry anyone from the third estate. 

D is correct because these were the noble families that were in the second estate. They only paid taxes during war time.