The greatest difference between Ben Jonson's "On My First Son" and "Song to Celia" is that the former is written in a mournful tone about the loss of a child, while the latter is written in a joyful and celebratory tone about romantic affection.
The question asks about the greatest difference between Ben Jonson's poem "On My First Son" and "Song to Celia". While both poems are elegies, they treat the elegiac convention differently, which influences their tone and subject matter. "On My First Son" is written in a serious and mournful tone as it is about the loss of a child and reflects the pain and sorrow of a father. In contrast, "Song to Celia" is written in a more romantic and joyful tone, expressing affection rather than mourning a loss.
Considering these facts, the correct answer to the student's question is option (b): "On My First Son" is written in a serious and mournful tone, while "Song to Celia" is written in a joyful and celebratory tone. This answer focuses on the tone and emotional content of the poems, which reflects a significant aspect of how each poem approaches the subject of death.