D. Catalyst
A catalyst is a reason for an event to occur.
The answer is A contrasting bright colors and dark colors.
A legend is a caption, a title or brief explanation appended to an article, illustration, cartoon, or poster.
A key is an explanatory list of symbols used in a map, table, etc.
Do you mean his sister?
she is demanding and mean.
he bosses him around.
her dolls are scary.
