Question

caribou (red diamonds) and wolf (blue dots) populations over years (1989–2005) with above - average winter snowfall (snowflakes). y - axes: caribou herd size (0–3500) and wolves/1000 sq. km (0–16). question: which two pieces of data suggest that winter snowfall affects the size of both the wolf and caribou populations? options: a. single winters with heavy snowfall were followed by decreases in both wolf and caribou numbers. b. caribou numbers declined in heavy snowfall years, and wolf numbers declined in normal snowfall years. c. the largest declines in wolf and caribou numbers occurred during six consecutive heavy snowfall winters. d. wolf and caribou numbers reached a dynamic balance during multiple years with normal winter snowfall. e. several years of normal snowfall produced an increase in wolf numbers followed by an increase in caribou numbers. (e is checked.)

Explanation:

• Option A: Single heavy snowfall winters followed by decreases in both populations shows a direct impact of heavy snowfall (winter snowfall) on both wolf and caribou numbers, suggesting causation.
• Option C: Six consecutive heavy snowfall winters with the largest declines in both populations also indicates that winter snowfall (heavy here) affects both populations as the declines coincide with heavy snowfall.
• Option B: Wolf numbers declining in normal snowfall years doesn't support snowfall affecting wolves, so incorrect.
• Option D: Dynamic balance in normal snowfall years doesn't show snowfall affecting population size (just balance), incorrect.
• Option E: Normal snowfall leading to increase in wolves then caribou doesn't show snowfall affecting size (shows a sequence but not impact of snowfall on size), incorrect.

Answer:

A. Single winters with heavy snowfall were followed by decreases in both wolf and caribou numbers.
C. The largest declines in wolf and caribou numbers occurred during six consecutive heavy snowfall winters.