Which insect resembles silverfish but is gray or brown instead of silver or blue?

Firebrats are indeed the correct answer because they are closely related to silverfish and exhibit similar behavior and anatomy. While silverfish are primarily recognized for their metallic silver coloring, firebrats appear in shades of gray or brown. Both insects belong to the same order, Thysanura, but firebrats have adapted to thrive in warmer environments, which affects their coloration and habitat preferences.

The other insects listed, such as carpenter ants and pavement ants, belong to different families and have distinct physical features and behaviors that do not resemble silverfish. Carpenter ants are large, black or reddish ants known for wood excavating, while pavement ants are small and often dark in color, commonly found in urban areas. Bald-faced hornets are wasps that are easily identifiable by their black and white coloration and nesting habits, which differ significantly from the characteristics shared by silverfish and firebrats. Thus, firebrats correctly fit the description provided in the question.