Answer the following question given this paragraph: 

Bacteria are the most abundant living things on Earth. They live in almost all environments. They are found in the air, ocean, soil, and intestines of animals. They are even found in rocks deep below Earth's surface. Any surface that has not been sterilized is likely to be covered with bacteria. The total number of bacteria in the world is amazing. It's estimated to be about 5 million trillion trillion. If you write that number in digits, it has 30 zeroes!.


Q: What is the most abundant living thing on earth that can be found in almost any environment?

 Choices:

- pests

- viruses

- pathogens

- bacteria

A:
bacteria
