Which type of organism is thought to be one of Earth's first organisms?

• A. Fungi
• B. Bacteria
• C. Protozoa
• D. Algae

Answer: (B)

Verified step by step guidance

1. Understand the context of the question: it asks about the earliest types of organisms on Earth, which relates to the origin and evolution of life.
2. Recall that Earth's first organisms were simple, single-celled life forms that appeared billions of years ago, long before complex multicellular organisms evolved.
3. Recognize that bacteria are prokaryotic microorganisms, meaning they lack a nucleus, and are among the oldest known life forms based on fossil and molecular evidence.
4. Differentiate bacteria from other options: fungi, protozoa, and algae are generally more complex and appeared later in evolutionary history.
5. Conclude that bacteria are considered one of Earth's first organisms due to their simplicity, early appearance in the fossil record, and ability to survive in harsh early Earth conditions.