Which element is required in comparatively least quantity for the growth of plant?

Which elements is required in comparatively least quantity for the growth of plant?

Which element is required by plants in the greatest amount?

The element which is required in largest quantity by plants is

Which of the following element is required in minor for the growth of plants but is extremely important for growth of animals ?

Which of the following element is required in minor for the growth of plants but is extremely important for growth of animals ?

Element required in least quantity is :-