Which of the following does not need an apostrophe inserted or deleted?

a. the music from the '80s has a more electronic sound than the music of the '70s.

b. the music from the '80's has a more electronic sound than the music of the '70's.

c. the music from the 80s has a more electronic sound than the music of the 70s

d. the music from the 1980's has a more electronic sound than the music of the 1970's.

Walking is not the most exciting form of exercise a person can take on for fitness. yet it is low impact and requires no fancy equipment. that makes walking a simple activity for those new to exercise. walking is less likely than other exercises to cause injury to leg tendons and muscles. all it requires is a good pair of sneakers-no cables, stylish outfits, or weights required. of course, a person could increase the benefit of a workout by adding weights or speed walking. identify the main idea of this paragraph. walking is a difficult and safe exercise for beginners. walking is an easy and safe exercise for beginners. walking is a boring and dangerous form of exercise. walking is an exciting and very effective form of exercise.