[单项选择]对土壤和作物都有利的垃圾堆肥肥料粒度为（）。
A. 2～5mm
B. ≤10mm
C. ≤2mm
D. ≤5mm
E. ≥5mm

Parents with an adopted child wonder whether, when and how to tell their child that he or she is adopted. They also want to know if there are special problems for an adopted child.
Child and adolescent psychiatrists (精神病学家) recommend that the child be told about the adoption by the adoptive parents. Children should be told about their adoption in a way that they can understand.
There are two different views on when a child should be told about the adoption. Many experts believe the child should be told at the earliest age possible. This approach provides the child an early opportunity to accept and integrate the concept of being "adopted". Other experts believe that telling a child too early may confuse the young child who can’t really understand the event. These experts ad vise waiting until the child is older.
In either case, children should learn of their adoption from the adoptive parents. This helps give the message that adopti
A. Adopted children recommend that they be told about the adoption by adoptive parents.
B. Experts all agree that telling the children too early about the adoption may confuse them.
C. Some experts hold that the adopted child should be kept in the dark as long as possible.
D. Parents should not discourage the adopted child from talking about the process of adoption.