The correct answer is D) All of the above. The disadvantages of using chain lashing on heavy vehicles aboard Ro-Ro vessels are: 1) It is heavy, which can make it difficult to handle and install properly. 2) The links in the chain can lose strength if placed over sharp corners or edges, compromising the effectiveness of the lashing. 3) Chain lashing does not absorb shock well, unlike other lashing materials like webbing or fiber ropes, which can lead to increased stress on the cargo and securing points. Therefore, the combination of these factors makes chain lashing a less desirable option for securing heavy vehicles on Ro-Ro vessels compared to other lashing methods that can better address weight, strength, and shock absorption requirements.