Final answer:
The most specific and effective sentence is: 'Lamar, saddened by his noble and honored grandfather's death, flung himself mournfully on his bed, sobbing.' as it vividly describes Lamar's deep sorrow and actions.
Step-by-step explanation:
The sentence "Lamar, saddened by his noble and honored grandfather's death, flung himself mournfully on his bed, sobbing." is the most specific and effective option among the given sentences. This sentence provides a vivid description of Lamar's actions and emotions using specific details: the nobility and honor of the grandfather, the act of flinging himself on the bed, and the act of sobbing express the depth of Lamar's sorrow very effectively. These elements contribute to a strong narrative writing using past tense, creating a clear and impactful image for the reader.