Final answer:
The butter spreader should be placed parallel to the fork with the blade turned to the left after use, following traditional table etiquette.
Step-by-step explanation:
The correct placement of a butter spreader after usage would traditionally be parallel to the fork, with the blade turned to the left. This table-setting rule follows general etiquette to avoid any confusion or inconvenience to fellow diners or staff clearing the table. Although the other options listed may seem plausible, the arrangement with the blade turned to the left while parallel to the fork is the one that is most often correct according to traditional Western dining etiquette.