The paragraph is about the importance of rules governing imports and pesticides. 'R' will be the first sentence as it talks about the proposed amendments . 'QS' will form a mandatory pair as the importance of pesticides is being talked about and pesticide is linking both the sentences. 'P' forms a mandatory pair with S6 as both talk about the measures to check the usage of pesticides in agriculture. The correct sequence will be 'RQSP'. So, option (b) is correct.