Question

24
select the correct answer.
what is the meaning of the phrase vital systems, as it is used in paragraph 5?
a. essential patterns
b. necessary components
c. simple techniques
d. complex structures

racing the clock to stem the spread of the mountain pine beetle
by korey morgan
office of communication, usda forest service
may 11, 2021
(1) in the summer of 2019, forest service entomologist amy lockner made her way along the taylor canyon road toward gunnison, colorado, a small mountain town situated in a valley often referred to as the \gateway to the rockies.\
(2) as she drove down the winding canyon road flanked by pine trees, her gaze caught a subtle inconsistency in the forest canopy that other travelers would not have noticed. what caught lockners eye was a group of lodgepole pines beginning to fade and discolor.
(3) the sudden realization hit her like a thunderclap. years of experience studying insect species and their effect on the environment trained her to look out for the tell-tale signs of mountain pine beetles. she took note of the spot, turned off the main road, and immediately looked for a nearby landowner to get permission to collect samples.
(4) \i knew that given the size and age class of the lodgepole pine on the hillside, it had to be mountain pine beetle,\ said lockner. \this is the same species that had killed so many millions of acres in colorado several years before, and i was overwhelmed. i knew i needed to act fast, especially if we had any chance of slowing it down.\
(5) mountain pine beetles burrow into pine trees to lay eggs. once the eggs hatch, the offspring feed on the living tree from the inside. over just a few weeks, the larvae destroy the trees vital systems. after several months, the tree turns red and brown as it dies. the cycle takes just one year, and the newly formed beetle is off to find their next host and begin it all again.
(6) as the population of beetles grows from an outbreak to an epidemic, they spread across tens of thousands of trees and cause mass death.

Explanation:

In paragraph 5, "vital systems" describes the critical, necessary parts of the pine tree that the beetle larvae feed on, which are required for the tree's survival. "Necessary components" matches this meaning, as these systems are essential parts that keep the tree alive.

Answer:

B. necessary components