'a', 'c', and 'd' are true for any two circles. That's because
ALL circles are similar. You don't need to prove it. The question
is weird.
No but it is true that the two equations are parallel.
Answer:
Area of a circle=πr²
radius is half of the diameter
1/2×2=1
π1²
22/7×1
3.1415926535897932
~3.14
B. -7
The answer all comes down to you getting -7/f.
Hope I helped!