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. For example, epidemiological studies looking for a relationship between cell phone use and brain cancer development, have been largely inconclusive, save to demonstrate that the effect, if it exists, cannot be a large one.
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?
YES.