TASK DEFINITION: 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.
PROBLEM: 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

SOLUTION: 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.

PROBLEM: Question: When food enters the stomach after a period of fasting, a drop in what initiates the conversion of pepsinogen to pepsin? Answer: ph

SOLUTION: Ph food enters the stomach after a period of fasting, a drop in what initiates the conversion of pepsinogen to pepsin.

PROBLEM: Question: What do seismic waves prove about the inner core? Answer: it is solid

SOLUTION:
Seismic waves prove the inner core it is solid.