Even spiders that do not build webs from silk use it or a va

Even spiders that do not build webs from silk use it or a variety of purposes,such as contructing egg sacs and nursery tents.
A.all spiders build webs.
B.spiders that build webs don't build egg sacs or nursery tents.
C.silk is used by all spiders.
顺便解释一下这个句子的意思,还有为什么会这么解释?
呵呵，是打错了~是of