I’m very sorry but I don’t know how to answer that question.
D. Ba and F. Took the test
The melting point of potassium = 
Melting point of titanium = 
Titanium has a stronger metallic bonding compared to potassium. Titanium being a transition metal has greater number of valence electrons (4 valence electrons) contributing to the valence electron sea compared to potassium which has only one valence electron. The atomic size of Titanium much lower than that of potassium, so the bonding between Titanium atoms is stronger than that of potassium. Hence, the melting point of Titanium is much higher than that of potassium.
Visible and infrared light do not cause sunburn and they are not known to directly be a skin cancer risk.