Answer:
option 4
Step-by-step explanation:
|a| represents Absolute value, it is the distance from zero that a number is on the number line. And we know distance cannot be negative.
So,


Using the Pythagorean theorem we can solve for the radius
see attached picture:
The answer is going to be 0.1775
1. a. {-2, -1, 0}
2. d. all real numbers (i think)
3. d. all real numbers (i think)