Let's look at these statements one at a time:
i.
This is a direct statement of De Morgan´s law. This is definitely true. Just to recap, De Morgan´s laws are as follows:
1.
2.
ii. , then is equal to the universal set
If A and B are disjoint sets, and is the universal set. This statement is correct.
iii. If = Universal Set, then should be the null set. This means is the null set.
iv. If , then
If then .
This implies that
If , then and
Thus . This statement is true.
Correct Answer: All four statements are true.