Generally, non-metals are not lustrous. Which of the following non-metal is lustrous? 

Lustre is an attribute of items that indicates how strongly they reflect light. Solid surfaces exhibit lustre when they reflect incident light. The existence of free electrons is the cause of this.

The presence of free electrons causes elements to display their lustrous nature. 

As we descend on the periodic table, the size of the atoms gets larger. More shells are added around the nucleus as the atomic size grows. The electrons become loosely bound as a result, and the effective nuclear charge drops. 

Although metals are shiny, in general Non-metals lack lustre, or shine, therefore they don't appear shiny.
Iodine is an exception to this quality. Iodine has an atomic number of 53. Iodine has a huge atomic size as a result. The valence electrons thus suffer an extremely low effective nuclear charge. An iodine atom's electrons are thus loosely bonded. Iodine is shiny as a result.

Hence, the correct answer is option D.