请教··prep1 104未划线部分 的平行问题

mia113

104
In Britain, "pig" refers to any member of the class of domestic swine, but the United States uses the

term when referring only to younger swine not yet ready for market and weighing less than 82

kilograms (180 pounds).

(A) the United States uses the term when referring

(B) the United States term refers

(C) in the United States the term refers

(D) in the United States they use the term as it refers

(E) it is used in the United States when referring
答案是C没有问题·想请问下大家·未划线部分 and连接的ready和weighing为什么可以平行吖？
一个是adj一个是现在分词吖？