In civil engineering, how do soil properties affect the stability, bearing capacity, and structural design of retaining walls?

a$)$ Soil cohesion influences the stability of retaining walls by:

i$)$ Increasing resistance to sliding along the soil$-$wall interface

ii$)$ Enhancing overall stability against overturning forces

b$)$ Angle of internal friction impacts retaining wall design by:

i$)$ Influencing the soil's ability to withstand lateral pressure

ii$)$ Affecting the choice of wall material and reinforcement

c$)$ Moisture content affects retaining wall stability by:

i$)$ Altering soil properties such as cohesion and angle of internal friction

ii$)$ Potentially leading to soil swelling or shrinkage, impacting wall bearing capacity

d$)$ All of the above.