Which of the following statements are correct regarding Westergard’s concept for temperature stresses?1. During the day, the top of the pavement slab gets heated under the sunlight when the bottom of the slab becomes hot2. During summer season as the mean temperature of the slab increases, the concrete pavement expands towards the expansion joints3. Due to frictional force at the interface, compressive stress is developed at the bottom of the slab as it tends to expand.

• A. 1 and 2 only
• B. 2 and 3 only
• C. 1 and 3 only
• D. 1, 2 and 3