Define crepuscular and describe when such mammals are active.

• A. Active at dawn and dusk; examples include many deer and some rodents.
• B. Active only during the night.
• C. Active only during the day.
• D. Always in solitary groups.

Answer: (A)

Crepuscular means being most active during twilight—around dawn and dusk. The best choice fits this timing and even names deer and many rodents as examples, which reflects how these animals often forage or move during those low-light periods. This twilight window helps them balance foraging with predator avoidance and heat management, depending on the species and environment. The other options describe different activity patterns: active only at night is nocturnal, active only during the day is diurnal, and being always in solitary groups relates to social behavior rather than when activity occurs.