Dead organisms can undergo various processes of decomposition and transformation to form different substances. However, it is important to note that the options provided in the question, coal, petroleum, and natural gas, are all formed over millions of years through natural geological processes. None of these substances can be prepared in a laboratory from dead organisms.

Explanation:

1. Coal:
- Coal is a fossil fuel that is primarily composed of plant matter that has undergone a process of transformation over millions of years.
- It is formed from the remains of dead plants that have been subjected to heat and pressure in the Earth's crust over geological time.
- Coal cannot be prepared in a laboratory from dead organisms as the formation process requires specific geological conditions over extended periods.

2. Petroleum:
- Petroleum, also known as crude oil, is another fossil fuel that is formed from the remains of marine organisms.
- It is primarily composed of hydrocarbons and is formed through a complex process involving the burial of organic material, heat, and pressure over millions of years.
- The formation of petroleum occurs in specific geological environments, such as sedimentary basins, and cannot be replicated in a laboratory setting.

3. Natural Gas:
- Natural gas is predominantly composed of methane (CH4) and is also formed from the remains of dead organisms.
- It is typically found in association with petroleum deposits and is formed through similar geological processes over long periods.
- Like coal and petroleum, natural gas cannot be prepared in a laboratory as its formation requires specific geological conditions and time scales.

Conclusion:
Based on the natural processes involved in the formation of coal, petroleum, and natural gas, it is evident that none of these substances can be prepared in a laboratory from dead organisms. Their formation requires millions of years, specific geological conditions, and natural processes of decomposition and transformation.