Please remember that a parallelogram is 4 parallel lines and the opposite sides are congruent. With that information you should be able to pick the correct answer.
If you are trying to find the slope of a line that is perpendicular to another line, you would need to change the sign and change it to the fraction's reciprocal.
m = 
Change the sign of the slope:

Finally, make the reciprocal of the original slope (switching the numerator and denominator):

Simplify:
3
Final answer:

Answer: center (1;0), radius = 2
Step-by-step explanation:
x² – 2x + 5+ y² = 8
x² – 2x + 5+ y² = x² – 2x + 1 + 4 + y² = (х-1)² +4 + y²
(х-1)² +4 + y² = 8
(х-1)² + y² = 8 - 4 = 4
(х-1)² + y² = 2²
center (1;0), radius = 2