Explanation:

- The Industrial Employment (Standing Orders) Act, 1946, outlines the process for how standing orders are to be established and enforced in industrial establishments.

- Under this Act, standing orders come into effect after a specified period following the dissemination of the Appellate Authority's order to both the employer and trade unions.

- Seven days (Option 1): This period is too short for the standing orders to take effect as per the Act’s stipulations.

- Ten days (Option 2): This duration also does not align with the Act's provision for the standing order's effectiveness.

- Fifteen days (Option 3): This option similarly does not meet the required time frame detailed in the Act.

- Thirty days (Option 4): This is the correct duration. The standing orders become operational thirty days after the order of the Appellate Authority is communicated.