task : $1\mathrm{.}20$@#What are the foundational theories that underpin the field of Civil Engineering, encompassing principles such as structural mechanics, materials science, and geotechnical engineering? Explore the significance of key theories like elasticity, plasticity, and stress analysis in designing resilient structures. How does soil mechanics theory contribute to the understanding of foundation design and stability? Discuss the application of fluid mechanics principles in hydraulic engineering and transportation systems. Furthermore, analyze how structural dynamics theory informs the design of earthquake$-$resistant buildings and bridges. Finally, examine the role of environmental engineering theory in addressing sustainability and resilience challenges in civil infrastructure projects.