SEE THE SENTENCE THIS WAY:
In the United States, more than half of all arrests for serious crimes against property
are [u]of 20 years olds or younger.
Now you cant say
1) ARRESTS are PERSONS
2) ARRESTS are 20 YEARS OLD
3) ARRESTS are of 20 yrs olds or younger
These all generates nonsensical meaning and hence are just incorrect.
NOW TO OPTIONS:a) of 20 years olds or younger
--> This option states that ARRESTS have some age--> ITS WRONG.b) 20 years old or younger
c) of persons 20 years old or younger
--> CORRECTd) persons 20 years old or lesse) 20 years old or less
Hope this helps...!!
Practice Practice and practice...!!
If my reply /analysis is helpful-->please press KUDOS
If there's a loophole in my analysis--> suggest measures to make it airtight.