Deficiency symptoms of an element tend to appear first in young leaves. It indicates that the element is relatively immobile. Which one of the following elemental deficiency would show such symptoms?

It is because, the immobile elements are first transported to the tip level of the plant and as Sulphur is an immobile element,which is required by young leaves, stem and root tips. So if the deficiency of Sulphur occurs it would lead to reduced growth, extensive root growth, hard and woody stem and chloriosis which is the yellowing of leaves due to lack of chlorophyll takes place.