Question

Form a union for the following sets.

K = {2, 3, 5, 8}

L = {3, 5, 7}

{ }
{3, 5}
{2, 3, 5, 7, 8}
{2, 7, 8}

Answer 1

to form a union of finite sets you get all unique elements. so you have
{2,3,5,7,8}
so it's the third answer
a union of the sets is a set that contains that contains both their elements and nothing else.
You should look up some set theory, or at least the basic definitions.