Answer:
b. desire.
Explanation:
Personification is a literary technique that gives human characteristics to non-human entities or ideas. In other words, when non-living things and abstract ideas are given living characteristics, that is known as personification.
In Petrarch's "Sonnet 18", the speaker talks about his love for his lady, most probably Laura, who's been the subject of all of his sonnets. And in the third stanza, we see him personifying death. He reveals, "I flee: but not so quickly that desire/does not come with me as is his wont." Here, the desire he's talking about is the desire to die, to "[see] the end of [his] light". And he's complaining that the desire to die does not come as swiftly as he had hoped, and unlike how death often happens. So, he's personifying that desire, referring it as "his".
Thus, the correct answer is option b.