Q1: Distribution reinforcement in a simply supported slab, is provided to distribute

ANS:D - all the above.

Distribution reinforcement in a simply supported slab is primarily provided to distribute the load. This reinforcement helps to evenly distribute the applied loads across the slab's cross-section, reducing localized stress concentrations and improving overall structural performance. However, distribution reinforcement can also help in mitigating temperature and shrinkage stresses to some extent. Temperature changes and shrinkage can lead to cracking in concrete structures, and distribution reinforcement can help control the width and extent of cracks by providing additional tensile strength and controlling crack widths. So, while the primary purpose of distribution reinforcement is to distribute load, it also contributes to managing temperature and shrinkage stresses to some degree. Therefore, the correct answer to your question is: "all the above."