A Steel Bracket $A B C \quad\left(E I=4.2 \times 10^{6} \mathrm{~N} \cdot \mathrm{m}^{2}\right)$

A steel bracket $A B C \quad\left(E I=4.2 \times 10^{6} \mathrm{~N} \cdot \mathrm{m}^{2}\right)$ with span length L = 4.5 m and height H = 2mis subjected to load P = 15 kN
At C. The maximum horizontal displacement of joint C is approximately: (A) $22 \mathrm{~mm}$
(B) $31 \mathrm{~mm}$
(C) $38 \mathrm{~mm}$
(D) $40 \mathrm{~mm}$