With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: The World Health Organization has classified radio frequency electromagnetic radiation as Group 2B - possibly carcinogenic. This group contains possible carcinogens such as lead, DDT, and styrene. By contrast, epidemiological studies looking for a relationship between cell phone use and brain cancer development, have shown that people who use cell phones more often actually exhibited less brain cancer than those who didn't own a phone, but were otherwise essentially identical in other regards, which thus demonstrates that any effect, even if it exists, cannot be large.
text_B: Would you say, reasonably, that the WHO's cautious stance is at least somewhat warranted, since it has not been contradicted by any scientific data?
NO.