Option 1: Sodium is not used in fireworks to create a brilliant white light. Sodium is commonly used in fireworks to create a yellow color.

Option 2: Magnesium is the correct answer. It is commonly used in fireworks because it produces a very bright and intense white light when ignited. This makes it ideal for creating a brilliant white flash in fireworks displays.

Option 3: Aluminium is not used to create a white light in fireworks. Instead, it is used to produce silver or silvery-white sparks.

Option 4: Silver is not commonly used in fireworks to produce a white light. Although it can produce a bright flash, it is more expensive and less commonly used compared to magnesium.

Therefore, the correct answer is option 2: Magnesium, as it is used in fireworks to create a brilliant white light.