Answer: Option 'B' is correct.
Explanation:
Since we have given that
Distance between the center and the chord = 0.7 cm
Radius of the circular ring = 2.5 cm
We need to find length of the chord.
Since it forms a right angle triangle.
So, we will use "Pythagorus theorem":

So, Length of chord is given by

Hence, Option 'B' is correct.