The submarining effect occurs...
A)when the seatbelt is worn very tightly.
B)when the headrest is not properly adjusted.
C)when the body slides under the lap belt because the seatbelt does not restrain it adequately.Correct
For the seatbelt to be effective and able to fulfil its function, it must be approved, properly anchored, adjusted and fitted to the body, and correctly fastened. A seat that is too reclined, or the use of unsuitable cushions or seat covers, can cause the occupant to slide under the belt in a traffic accident (submarining effect).