Let $$R (a, b, c)$$ and $$S(d, e, f)$$ be two relations in which $$d$$ is the foreign key of $$S$$ that refers to the primary key of $$R.$$ Consider the following four operations $$R$$ and $$S$$
(a) Insert into $$R$$ (b) Insert into $$S$$
(c) Delete from $$R$$ (d) Delete from $$S$

Which of the following statements is true about the referential integrity constraint above?

Given $$\sqrt {\left( {224} \right),} = {\left( {13} \right)_r},$$
The value of the radix' $$r$$ is:

Let $$^ * $$ be defined as $${x^ * }y = \overline x + y,$$ Let $$z = {x^ * }y.$$ Value of $${z^ * }x$$ is

Let $$f\left( {x,y,z} \right) = \overline x + \overline y x + xz$$ be a switching function. Which one of the following is valid?