An $18.0$ Pm Wavelength Photon Is Scattered by a Stationary Electron Through

An $18.0$ pm wavelength photon is scattered by a stationary electron through an angle of $120 ^ { \circ }$ .
What is the wavelength of the scattered photon? (melectron $= 9.11 \times 10 ^ { - 31 } \mathrm {~kg} , c = 3.00 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } , h$ $\left. = 6.626 \times 10 ^ { - 34 } \mathrm {~J} \cdot \mathrm { s } \right)$

A) $19.2 \mathrm { pm }$
B) $24.1 \mathrm { pm }$
C) $21.6 \mathrm { pm }$
D) $22.9 \mathrm { pm }$
E) $20.4 \mathrm { pm }$