I believe it is "C. Cotton sheets" because cotton is a renewable resource and since it is a sheet it is sure to be entirely made of cotton

C: cotton sheets.  reason of answer/evidence: cotton sheets can be made out of any type of wood that includes from fallen trees, paper-like material, wood pulp sheets, any type of forestry which makes it able to be made of renewable resources. confused about what i mean by this? so you know how students (like us) use paper to write on? we throw paper away in the recycle bin because its made from trees , or , wood. simple.