Answer:
a control variable is a variable or an element wich is held constant throughout an experiment o a research in order to assess the relationship between multiple variables.
Answer:
The subject
Explanation:the topic is the subject of a speech, essay, or discourse
Answer: D
Explanation: The story exactly supports this
Answer:its D it informs the reader about Pluto's planetary status
Explanation:
D all of the above because he was involved in all of those events