# D and E are the points lying on AB and AC respectively such that BC

Suppose ABC is a triangle with AB of unit length. D and E are the points lying on AB and AC respectively such that BC and DE are parallel. If the area of triangle ABC twice the area of triangle ADE, then the length of AD is

(a) 1/2 unit

(b) 1/3 unit

(c) 1/sqrt.2 unit

(d) 1/sqrt.3 unit