The correct answer is: B. Vibro pile
A vibro pile is a type of foundation pile that is driven into the ground by a vibratory hammer. The vibration loosens the soil and allows the pile to be driven more easily. Vibro piles are often used in soft soils that have little resistance to the flow of concrete.
A simplex pile is a type of foundation pile that is driven into the ground by a hammer. The pile is made of steel or concrete and has a pointed tip. Simplex piles are often used in firm soils.
A Raymond pile is a type of foundation pile that is driven into the ground by a hammer. The pile is made of steel or concrete and has a flared base. Raymond piles are often used in soft soils.
A Franki pile is a type of foundation pile that is driven into the ground by a hammer. The pile is made of concrete and has a cylindrical shape. Franki piles are often used in hard soils.
Vibro piles are the best type of piles for soft soil having little resistance to the flow of concrete because they are easy to drive and provide good support in soft soils.