The correct option is D Wanting to separate from his body.
In the first line of the poem, the poet is requesting his heart to hold on for a little while longer. In the second line he asks the heart to not part even though the present looks 'blighted' or destroyed and the future looks 'gloom' or full of darkness. Therefore, it appears that the heart wants to separate from the body. So, the most apt answer is option D). The other sentences are not the correct interpretation of what the poet means to convey and therefore are incorrect answers to the given question.