A vessel of what range in length shall not be obliged to give the bell signals of Rule 35?

The correct choice refers to vessels that are between 12 to 20 meters in length, as these vessels are not required to give the bell signals as stated in Rule 35 of the International Regulations for Preventing Collisions at Sea (COLREGs). Rule 35 specifically outlines the requirements for sound signals in restricted visibility, indicating when vessels must signal their presence to avoid collisions.

Vessels less than 12 meters are generally not obliged to comply with many of the sound signaling requirements due to their limited capability and size, allowing them to operate with greater flexibility in these conditions. On the other hand, vessels over 20 meters in length typically need to follow the regulations closely to ensure safety and communication with other vessels. Therefore, it is the range of 12 to 20 meters that falls into a specific category where the obligation to give bell signals is waived, allowing for practical operation within a standardized framework of maritime law.