Answer
See explanation below.
Work Step by Step
(a) Consider $x$ and $y$ are both real numbers. For every real number $x$ there must exist a real number $y$ such that $x \lt y$.
(b) When both real numbers $x$ and $y$ are both non-negative then there product will also be no-negative.
(c) Consider $x$ and $y$ are both real numbers. For every real numbers $x$ and $y$ there must exist a real number $z$ such that $xy=z$.
