Explanation:

- Presumptions: These are legal assumptions accepted by the court. They can shift the burden of proof to the opposing party, as they must disprove the presumption.

- Admissions: When a party admits a fact, it reduces the burden on the other party to prove that fact. This simplifies the case by establishing accepted truths.

- Estoppels: This prevents a party from arguing against or denying something they've previously said or agreed to, leading to a lighter burden on the opposing party.

Option 4: All the above lightens the burden of proof by using presumptions, admissions, and estoppels effectively.