While both are on the high frequency end of the spectrum, ultraviolet has the higher frequency. Infrared radiation has a lower frequency and less radiant energy so when it interacts with matter, it causes the molecules to vibrate and result in heat emission. On the other hand ultraviolet radiation possesses a higher frequency and higher radiant energy therefore when molecules in matter are exposed to UV they collide more violently sometimes causing a change in its atomic or molecular structure and ultimately its chemical composition.
Your answer should be the second choice. While both are on the high frequency end of the spectrum, ultraviolet has the higher frequency. Hope this helps!
