Consider the following statements:

In subsoil exploration programme the term "significant depth of explortion" is up to

1.   the width of foundation.

2.   twice the width of foundation.

3.   the depth wherethe additional stress intensity is less than 20% of overburden pressure.

4.   The depth where the additional stress intensity is less that 10% of the overburden pressure.

5.   hard rock leve.

Of these statements