The correct option is B 2:1
It is given that, AD = DB
i.e., AD = 12 AB
Also, as AE = EC
we have, AE = 12 AC
By mid-point theorem, we know that the line segment connecting the midpoints of two sides of a triangle is parallel to the third side and is congruent to one half of the third side.
i.e., DE || BC and DE = 12 BC
Thus, BC : DE = 2 :1