Please help me someone

When you answer this can you explain

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

Which sentence uses an objective tone? we will plant the best garden of any school in the area. the new campus garden will surely be envied by other schools. a garden would provide numerous benefits to the students. you will probably agree that gardens have many benefits.