The correct answer is: Only conclusion II follows.
The statement says that after this amendment to the Constitution, no child below the age of 14 years will be employed to work in any factory or mine or engaged in any other hazardous employment. This does not mean that before this amendment, children below 14 years were employed to work in factory or mine. It is possible that before this amendment, children below 14 years were not employed to work in factory or mine. The amendment could have been passed to prevent children below 14 years from being employed in the future.
Conclusion II follows from the statement. The employers must now abide by this amendment to the Constitution. This means that the employers must not employ children below 14 years to work in any factory or mine or engaged in any other hazardous employment.
Conclusion I does not follow from the statement. The statement does not say anything about whether or not children below 14 years were employed to work in factory or mine before this amendment.