问题：

[单选] Which of the following is/are TRUE regarding lashing requirements to secure vehicles aboard Ro-Ro vessels? （）

A . The securing of cargo on flats and trailers and in containers must be adequate to withstand both road and sea motions
B . The generally recommended lash angle cannot be greater than 45 degrees relative to the deck inany direction
C . It is necessary for an adequate number of securing points on the vehicles themselves in order that lashings may be properly and safely utilized
D . All the above