In which of the following levels of classification are the members most similar?

Step 1: Analyze the question The question asks which taxonomic level groups organisms that are most similar to one another.

Step 2: Explain the concept Classification moves from the broadest group to the narrowest:

Kingdom → Phylum → Class → Order → Family → Genus → Species

• As you move down the hierarchy, each group has fewer members, and those members share more characteristics.
• As you move up, groups get larger and the members share fewer features.

A handy way to remember the order is: King Philip Came Over For Good Soup.

Step 3: Compare the options

• D. Phylum is a very broad group, so its members share only a few basic features.
• A. Order is narrower than phylum, but its members still differ quite a lot.
• B. Genus groups closely related species, so the similarity is high.
• C. Species is the lowest level. Its members are so similar that they can interbreed and produce fertile offspring.

Step 4: Identify the answer Species is the lowest and most specific level in the list, so its members are the most similar.

Step 5: Exam tip For "most similar" questions, pick the lowest level in the hierarchy (species). For "least similar" or "most diverse" questions, pick the highest level (kingdom, or phylum if kingdom is not listed). Also remember that a species is a group of organisms that can interbreed to produce fertile offspring.