Explanation:

- The diameter of the circle is 10 m, so its radius (r) is 5 m.

- Chord 1 is 8 m long. Its distance from the center is found using the formula:

\( d_1 = \sqrt{r^2 - (l_1/2)^2} = \sqrt{5^2 - 4^2} = \sqrt{25 - 16} = 3 \) m.

- Two parallel chords are 6 m apart. So, the distance from the center to chord 2:

\( d_2 = 6 - d_1 = 6 - 3 = 3 \) m, but this would only be if the chords are on the same side from the center, which is not possible as the answer would repeat length or have negative value.

- The other chord is also at 3 m from the center (opposite side), so its length:

\( l_2 = 2\sqrt{r^2 - d_2^2} = 2\sqrt{25 - 9} = 2 \times 4 = 8 \) m.

- Therefore, the correct answer is:

- Option:4- 8 m

- Other options:

- Option:1- 10 m — Not possible, as that's the diameter.

- Option:2- 6 m — Not supported by calculations.

- Option:3- 4 m — Too short.

- So, the correct answer is Option:4- 8 m.