Answer:
1. Some scholars believe that Queen Elizabeth’s England was the Western world's first modern police state.
- The apostrophe "s" is added to "Elizabeth's" and "Worlds" in this sentence because apostrophes are added to single and plural nouns and unclear pronouns.
2. It is easy to poke fun at the clothing styles of the ‘70s and ‘80s.
- Apostrophes were used to replace the missing numerals in this sentence before the 70s and 80s.
3. Conservation of our planet's natural resources is everyone's concern.
- The apostrophe "s" is added to "planet’s" and "everyone’s" in this sentence because apostrophes are added to single and plural nouns and unclear pronouns.