Final answer:
Christianity is the religion with the largest number of followers, boasting approximately 2.2 billion adherents worldwide.
Step-by-step explanation:
Of the options presented, Christianity has the largest number of adherents, making it the world's largest religion. As of the information provided, Christianity has approximately 2.2 billion followers, and the number has been growing. While Islam is the fastest-growing religion and may surpass Christianity by 2020, as of the data available, it remains in second place with about 1.5 billion followers.
Hinduism is the third-largest religion with roughly 900 million adherents, while Judaism, also one of the world's major monotheistic religions, has a smaller number of followers compared to the others listed.