Which would most likely appear in an objective summary:
a. christina catnese argues that rain barreles are an easy, effective, and inexpensive way to conserve water.
b. the article explains the benefits of rain barreles, but i don't think i'd ever fill my fish tank with rainwater
c. rain barreles hardly seem worth the time or effort.
d. everybody should want to make positive contributions to the environment.

The option that would most likely appear in an objective summary is A. Christina Catnese argues that rain barrels are an easy, effective, and inexpensive way to conserve water.
This is the only objective summary among these examples - the other options show a subjective and personal opinion about something, which is not based on facts, but rather personal feelings. This is the reason why they cannot be objective.