A Container Has a Vertical Tube, Whose Inner Radius Is $900 \mathrm {~kg} / \mathrm { m } ^ { 3 }$

A container has a vertical tube, whose inner radius is 20.00 mm, connected to it at its side, as shown in the figure. An unknown liquid reaches level A in the container and level B in the tube -level A being 5.0 cm higher than level B. The liquid supports a 20-cm high column of oil, between levels B and C , whose density is $900 \mathrm {~kg} / \mathrm { m } ^ { 3 }$
The density of the unknown liquid is closest to

A) $3600 \mathrm {~kg} / \mathrm { m } ^ { 3 }$
B) $3900 \mathrm {~kg} / \mathrm { m } ^ { 3 }$
C) $3100 \mathrm {~kg} / \mathrm { m } ^ { 3 }$
D) $3300 \mathrm {~kg} / \mathrm { m } ^ { 3 }$
E) $2800 \mathrm {~kg} / \mathrm { m } ^ { 3 }$