Step 1: Understanding pesticide classifications
- Organochlorides (B): These were among the earliest synthetic pesticides introduced in the 1940s. Examples include DDT.
- Organophosphates (A): These were developed later to replace organochlorides due to environmental concerns.
- Sodium chlorate (C): This is a herbicide that became widely available later.
Step 2: Arranging them chronologically
Since Organochlorides were developed first, followed by Organophosphates, and finally Sodium Chlorate, the correct order is:
\[
B, A, C
\]