Which sentence is compound?

a. Do Max or Brian play on a little league team?

b. My uncle once played for a college football team and won several awards one year.

c. I have played on several different little league teams over the past three years.

d. I like all sports, but I enjoy football the most.

"d. I like all sports, but I enjoy football the most."

is the correct answer. A compound sentence is one that has two independent clauses that have been connected via either a semicolon, or a comma and a conjunction. Since "I like all sports" and "I enjoy football the most" are both independent clauses, and the sentence contains the conjunction "and", (d.) must be the correct answer.