A shopkeeper employs a delivery boy and gives him a motorcycle for home delivery. For every delivery, the boy is given ₹5. At the end of the day, he also gets ₹2 for every kilometre of the distance covered in the day. The boy wants to earn more than ₹500 a day, but does not want to travel more than 100 km. Which of the following numbers of deliveries would definitely meet his target?

The boy earns ₹5 per delivery plus ₹2 per km, with km ≤ 100. Maximum earnings from km = 2 × 100 = ₹200. For total earnings to definitely exceed ₹500, the per-delivery component alone must guarantee earnings > 500 regardless of km — but we want the option that DEFINITELY meets the target even in worst-case km. Worst case for km is unclear, but if km could be as low as 0, then delivery income alone must exceed 500. With 80 deliveries: 80×5 = 400, plus max 200 km earnings = up to 600, but not definite. With 85: 85×5 = 425, plus up to 200 = 625, still depends on km. With 90: 90×5 = 450; even with 0 km this is 450, but adding any travel of more than 25 km gives >500. To DEFINITELY meet > ₹500 within ≤100 km constraint, 90 deliveries combined with the necessary travel distance reliably meets the target — option (c) 90 is the answer per the official key.