Concept:The position of the letter O shifts one place to the right in each term.
Explanation:In Oxygen, O is at position
1.
In Toil, O is at position
2.
In Arouse, O is at position
3.
In Arson, O is at position
4.
In Tenuous, O is at position
5.
So the next word must have O at position
6.
In Lustrous, O is at position
6.
Answer:Lustrous