What does "marred" mean?

The term "marred" refers to something that has been damaged, spoiled, or blemished, which directly aligns with the meaning of "impaired the perfection of." When something is marred, it signifies that its original condition or quality has been negatively affected in some way, leading to an undesirable alteration of its state or appearance.

In this context, "impaired" indicates a reduction in quality or effectiveness, highlighting how an ideal state can be disrupted. The other choices do not convey this idea of damage or alteration; for instance, "enhanced" suggests an improvement, "completed successfully" implies a successful end, and "unchanged" indicates no alteration at all. Therefore, the selection that best captures the essence of "marred" is the one that reflects the idea of a decrease in quality or beauty.