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.

[EX Q]: Question: What begins approximately six weeks after fertilization in an embryo? Answer: ossification
[EX A]: Ossification begins approximately six weeks after fertilization in an embryo.

[EX Q]: Question: Which unit is used to express the amount of energy in food? Answer: Calorie
[EX A]: A calorie is used to express the amount of energy in food.

[EX Q]: Question: What is the wheeled robot developed by nasa to explore the surface of mars? Answer: mars rover
[EX A]:
The mars rover is the wheeled robot developed by nasa to explore the surface of mars.