If S is the set of distinct values of 'b' for which the following system of linear equations

x + y + z = 1

x + ay + z = 1

ax + by + z = 0

has no solution, then S is:

- an empty set
- an infinite set
- a finite set containing two or more elements
- a singleton

**Answer**

Here,

For a = 1, the equations become

x + y + z = 1

x + y + z = 1

x + by + z = 0

These equations give no solution for b = 1

Therefore, S is singleton set.

**The correct option is D.**