Final answer:
The external oblique ridge is a linear prominence of bone located on the external surface of the body of the mandible, making option 1) the correct answer.
Step-by-step explanation:
The external oblique ridge is a feature of the mandible, which is the lower jawbone in human anatomy. Regarding the options provided, the correct answer is 1) A linear prominence of bone located on the external surface of the body of the mandible. This ridge can be palpated or seen on a dried skull, running downwards and forwards from the anterior border of the ramus of the mandible. It's distinct from the mylohyoid line, which is a ridge located on the inside of the mandible where the mylohyoid muscle attaches, and the alveolar processes that support the teeth in both the maxilla and mandible.