The answer choices to this question are in the attached file. The effect of the word "surplice" is:
A. It reinforces the difference between the natural things the speaker holds dear and the rituals of the church.
"Some Keep the Sabbath Going to Church" is a poem by Emily Dickinson (1830-1886) in which the speaker talks about keeping the Sabbath.
When the speaker mentions the "surplice," the garment worn by the clergy, she is emphasizing the difference of her Sabbath to other people's Sabbath.
The speaker prefers to stay at home, with her family and her garden. To her, staying at home is Heaven already.
Other people "keep the Sabbath in Surplice," that is, would rather go to church to secure their place in Heaven when they die.
In other words, the speaker is already in Heaven, while others only wish to be.
In conclusion, the word "surplice" reinforces the difference between the natural things (garden, family) that the speaker holds dear and the rituals of the church.