The relationship between species of columns 1 and 2 describes

Saguaro cactus is keystone species of desert as it grows large number of fruits in hottest period of summer and provides shelter to rats and snake. Deciduous trees are the abundant species of temperate deciduous forest and provide food to deer (herbivore); fox are omnivores; shedding of leaves during autumn affects the whole food chain. Moose is herbivore of Taiga biome and is one of the few species that can digest pine and sprue needles. Lynx is carnivore of taiga biome and mainly feeds on snowshoe hare (a herbivore). Periodic fluctuation in population of snowshoe hare caused by unavailability of food during winters affect the lynx population. The Caribou or Reindeer of Tundra feeds on mass and lichen present beneath the artic surface during wintertime when vegetation is not available. Lemmings are stable food for snowy owl; these owls have keen eyes sight and hearing to find their prey hidden under lichen and snow cover. Thus, the correct answer is option A.