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.

Example Input: Question: What planet is the easiest to observe? Answer: mars
Example Output: Mars planet is the easiest to observe.

Example Input: Question: What do you call a substance that cannot be broken down to other substances by chemical reactions.? Answer: an element
Example Output: You call a substance that cannot be broken down to other substances by chemical reactions an element.

Example Input: Question: What kind of system do echinoderms possess? Answer: water-based circulatory
Example Output:
Echinoderms possess a water-based circulatory system.