Structural bulkheads on a ship are usually ____________.

A、Structural bulkheads on a ship are usually ____________.
B、Structural bulkheads on a ship are usually ____________.
C、Structural bulkheads on a ship are usually ____________.
D、Structural bulkheads on a ship are usually ____________.
E、Structural bulkheads on a ship are usually ____________.
F、Structural bulkheads on a ship are usually ____________.
G:Structural bulkheads on a ship are usually ____________.
H:Structural bulkheads on a ship are usually ____________.