mehrasa wrote:could you please say why both together are not sufficient>
to me bth stat is like this
region B+C+D+Small region are (respectively) 2+1+1/2+1/2=4x=800 the we can find area of region D

Don't let the diagram mislead you. Don't assume that the diagram is that of a square plot. No, it is not! It is just a representation of areas.

Question: What is the area of region D?
Given: Area of (A + B + C + D + unnamed) = 1600 Acres

1) Region D has 50% of the area of of region C, and region C has 50% of the area of region B.

Area of D = 0.5* Area of C
Area of C = 0.5* Area of B
Area of (A + B + C + D + unnamed) = 1600 Acres
Area of (A + B + 0.5*B + 0.5*0.5*B + Unnamed) = 1600 Acres
We now have, three variables(A,B,Unnamed) and One equation.
Insufficient!

2)Area of region A = 800 Acres

Area of (A + B + C + D + unnamed) = 1600 Acres
Area of (800 + B + C + D + unnamed) = 1600 Acres
We now have, four variables(C,B,D,Unnamed) and One equation.
Insufficient!

From 1 and 2

Area of (800 + B + 0.5*B + 0.5*0.5*B + unnamed) = 1600 Acres
Area of (1.75*B + unnamed) = 800 Acres
We now have, two variables(B,Unnamed) and One equation. Insufficient!
Option E

using both

B+C+D+x = 800
B = ?
x= ?
hence insufficient.
E it is.

Diagrams in DS are drawn to confuse sometimes -here the diagram makes it look like you can figure out what portion of the bottom section D is. However, there is nothing to indicate that and you cannot trust the figure on DS.