Chose Deurterium because a Heavy Water plant is located near my home town. So D wins for the nostalgia element. Yep, Nostalgia wins over every thing else once you cross 30. Also the other elements starting with D are mostly transuranic ones and did not have many interesting facts. And so it is Deuterium or Heavy Hydrogen.
It is thought that nearly all deuterium found in nature was produced in the Big Bang 13.8 billion years ago, and that the basic or primordial ratio of hydrogen-1 (protium) to deuterium (about 26 atoms of deuterium per million hydrogen atoms) has its origin from that time.
The discovery of deuterium/protium ratios in a number of comets very similar to the mean ratio in Earth’s oceans (156 atoms of deuterium per million hydrogens) has led to theories that much of Earth’s ocean water has a cometary origin.
Through much of the few minutes after the big bang during which nucleosynthesis could have occurred, the temperature was high enough that the mean energy per particle was greater than the binding energy of weakly bound deuterium; therefore any deuterium that was formed was immediately destroyed. This situation is known as the deuterium bottleneck.
Deuterium is produced for industrial, scientific and military purposes, by starting with ordinary water—and then separating out the heavy water by the Girdler sulfide process, distillation, or other methods.
Deuterium is used in heavy water moderated fission reactors, usually as liquid D2O, to slow neutrons without high neutron absorption of ordinary hydrogen. This is a common commercial use for larger amounts of deuterium.
During World War II, Nazi Germany was known to be conducting experiments using heavy water as moderator for a nuclear reactor design.Ultimately it led to the Allied operation called the “Norwegian heavy water sabotage”, the purpose of which was to destroy the Vemork deuterium production/enrichment facility in Norway.
India is the world’s largest producer of heavy water through its Heavy Water Board and also exports to countries like Republic of Korea and the US.
Refences: wikipedia, Heavy Water Board, India