Step 1: Understanding the Concept:
Pesticides are categorized into inorganic (based on minerals like Copper or Sulfur) and organic (carbon-based, often synthetic). The mid-20th century saw the transition from inorganic "First Generation" pesticides to synthetic organic "Second Generation" pesticides.
Step 2: Detailed Explanation:
- Bordeaux mixture (Option 1): Discovered in 1882, it is an inorganic fungicide made of Copper Sulfate and Lime.
- Burgundy mixture (Option 2): Similar to Bordeaux but uses Sodium Carbonate; it is also inorganic.
- DDT (Option 3): Dichlorodiphenyltrichloroethane was synthesized in 1874, but its insecticidal properties were discovered by Paul Müller in 19 It became the first synthetic organic pesticide to be used on a massive commercial and global scale starting in the 1940s. Its success triggered the modern agrochemical era.
- 2,4-D (Option 4): A synthetic organic herbicide discovered in the 1940s, slightly later than the insecticidal application of DDT.
In the context of the "first organic pesticide" in the modern synthetic sense, DDT is the definitive answer.
Step 3: Final Answer:
DDT was the pioneering synthetic organic compound that launched the large-scale commercial pesticide industry in the 1940s.