In rural road construction, the use of which of the following is preferred for ensuring environmental sustainability or to reduce carbon footprint ? 1. Copper slag 2. Cold mix asphalt technology 3. Geotextiles 4. Hot mix asphalt technology 5. Portland cement Select the correct answer using the code given below :

Copper slag (industrial waste), cold mix asphalt (low-temperature processing), and geotextiles (soil reinforcement) are preferred because they minimize resource extraction, reduce fuel consumption, and lower greenhouse gas emissions. In contrast, hot mix asphalt and Portland cement are excluded because their production and application are highly energy-intensive and involve significant carbon dioxide emissions. The core concept tested is "Green Technology in Infrastructure," specifically the use of sustainable materials and energy-efficient construction methods promoted under initiatives like the Pradhan Mantri Gram Sadak Yojana (PMGSY).