In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

Question: Organisms categorized by what species descriptor demonstrate a version of allopatric speciation and have limited regions of overlap with one another, but where they overlap they interbreed successfully? Answer: ring species
Organisms categorized by ring species species descriptor demonstrate a version of allopatric speciation and have limited regions of overlap with one another, but where they overlap they interbreed successfully.

Question: What forms a ketone when oxidized? Answer: secondary alcohol
Secondary alcohol forms a ketone when oxidized.

Question: What forms when one substance dissolves into another? Answer: solution

A solution forms when one substance dissolves into another.