Even-aged management practices involves clearing trees that
a. are all the same height
b. are all the same weight
c. are all near the same age
d. are all of widely different ages

C. Are all near same age.

Explanation:

Even-aged firewood management practices refer to the practice of clearing of trees that "are all near the same age"as this technique is usually adopted to maintain the proportion and continuity of various species of trees(thus, cutting of the trees of same age).  This practice is employed to minimize the costs and attain a coeval and comrade group of trees. It proves quite beneficial in reestablishing the succession of a native breed. It involves the selection of trees at first depending on the size, desirable species, etc. followed by clearcutting of unmerchantable(undesired) trees. This technique is usually adopted to maintain the proportion and continuity of various species of trees.