What are the most common types of shallow foundations for small buildings? I - Direct foundations are used where the layers of the subsoil, just b...

What are the most common types of shallow foundations for small buildings?

I - Direct foundations are used where the layers of the subsoil, just below the structure, are capable of supporting the loads.
II - The foundation beam can be considered the foundation itself. In the case of firm terrain and small loads, this type of shallow and very economical foundation can be used.
III - The pedestal is a type of foundation that can be made of concrete or a trunk of a cone. They are relatively tall and resist mainly by compression.
IV - Isolated or continuous footings are concrete support elements, lower in height than blocks, which resist mainly by bending. They are a direct foundation, usually reinforced concrete, with the approximate shape of a plate on which columns, pillars or even walls are supported. They can be continuous or isolated.
a) I and II are correct.
b) II and III are correct.
c) III and IV are correct.
d) I and IV are correct.