Question

spiderwebs are...
a mainly used to attract mates.
b used to catch food but can also be pretty.
c where spiders sleep at night.
d mostly for decoration.

Explanation:

Spiderwebs are primarily used to catch food (insects, etc.). And some spiderwebs can have a certain aesthetic quality (be pretty). Option A is incorrect as attracting mates is not the main use. Option C is wrong as spiders don't mainly sleep in webs. Option D is incorrect as decoration is not the main purpose.

Answer:

B. used to catch food but can also be pretty.