一個英語問題

1 making
the second part of this sentence is refering to European football, it can be written in another separate sentence:european football is played in 80 countries .This makes it the most popular sport in the world.
on combining the two sentences, the second one have to be changed to a noun clause, in which there exists no verbs.therefore, the verb" make" have to be written as making to act as a noun(gerund)