What are compound subjects please explain in your own words.

They are two or more words combined to make a statement

a compound subject is like it consists two or more simple subject loke a verb or a verb phras .these subjects consists only simple subjects , it does not include modify words.or modify

Exaplation: example, my son and their rule this kingdom in that sentence it will be "son" and "heir" refer to the same person.

answer; i believe the correct answer is (4) flip a coin as each participant arrives,heads indicates assignment to the first group: tails indicates assignment to the second group;

b) to encourage free trade