Based on the field notes provided for cross sections, what is the ground elevation at a point $18ft$ right of centerline at station $12+00?$ All units are in feet.

Field Notes

$($A$)42\mathrm{.}5ft$

$($B$)46\mathrm{.}9ft$

$($C$)49\mathrm{.}5ft$

$($D$)53\mathrm{.}9ft$