What is the length of BC?
A. 6 2/3 cm
B. 5cm
C. 4cm
D. 6cm

Thought I already answered this. I must have forgotten to click "add your answer."
We have similar triangle trianges ABC ~ ADE so
BC:AB = DE:AD
BC:2 = 10 : (2+3) = 10:5 = 2:1
So BC=4 because 4:2 = 2:1
Choice C.