Step 1: Identify the source of the line.
The line "A pulse in the eternal mind" is from Walt Whitman’s poem *Song of Myself*, which is part of his collection *Leaves of Grass*.
Step 2: Analyze each option.
- (A) Snake: Incorrect. This line is not from the poem *Snake* by D. H. Lawrence.
- (B) Song of Myself: Correct. The line is from Walt Whitman’s *Song of Myself*, which explores themes of the self and the cosmos.
- (C) Ode to Autumn: Incorrect. This is a poem by John Keats, unrelated to the line.
- (D) The Soldier: Incorrect. This poem by Rupert Brooke does not contain the line in question.
Step 3: Conclusion.
"A pulse in the eternal mind" is from *Song of Myself* by Walt Whitman.