Critical Reasoning

Source: Kaplan Verbal Workbook

The cause of the peculiar columnar growth pattern displayed by junipers growing near burning underground veins of lignite coal has never been convincingly explained. Until recently, the accepted theory posited that the abundance of carbon monoxide in the local atmosphere caused the columnar growth. However, a new theory holds that the cause is the persistent heat present near these underground fires which, while not intense enough to inflame the trees, can nonetheless change their normal growth pattern.

The existence of which of the following would provide the strongest support for the new theory?

A. A columnar juniper growing in an atmosphere of intense heat and an absence of carbon monoxide.
B. A normal juniper growing in an atmosphere of intense heat and an absence of carbon monoxide.
C. A columnar juniper growing in an atmosphere of normal heat and a high concentration of carbon monoxide.
D. A normal juniper growing in an atmosphere of intense heat and a high concentration of carbon monoxide.
E. A columnar juniper growing in an atmosphere of intense heat and a high concentration of carbon monoxide.

OA: A

Please explain