The correct option is B 5.5 cm
In △CEG and △DEF,
∠CEG=∠DEF (Common angle)
∠ECG=∠EDF (Corresponding angles, since BD || AE)
∠EGC=∠EFD (Corresponding angles, since BD || AE)
Hence, △CEG∼△DEF, BY AAA
Thus, DFCG=DECE
DF11=DEDE+CD (Given, CD = DE)
DE11=12
DE=5.5cm