The correct answer is option 1, which states that all three options - pumping of water to the reactors, use of boric acid, and taking out the fuel rods and keeping them in a cooling pond - may be adopted for cooling the nuclear reactors in the case of a nuclear disaster.

Let`s dissect each option to better understand them:

1. Pumping of water to the reactors: This involves continuously pumping water into the reactors to cool them down and prevent overheating. The water absorbs the excess heat generated by the nuclear reactions.

2. Use of boric acid: Boric acid is often used as a neutron absorber in nuclear reactors. By adding boric acid to the reactor coolant, the concentration of neutrons (which sustain the chain reaction) can be reduced, thereby helping to control the reactor`s operation and prevent overheating.

3. Taking out the fuel rods and keeping them in a cooling pond: This option involves removing the fuel rods from the reactor and placing them in a cooling pond. The cooling pond provides a controlled environment where the fuel rods can cool down gradually and prevent the release of radioactive materials.

It`s important to note that each option plays a vital role in cooling the nuclear reactors during a disaster, and hence, all three options may be adopted.