Explanation:

- The Petersberg Climate Dialogue is an international forum for discussing climate policy and collaboration.

- The 2020 dialogue was held virtually due to the COVID-19 pandemic.

- Germany has been a frequent host of this dialogue to strengthen global climate action.

- Option 1: Germany hosted the 2020 dialogue, focusing on global climate strategies.

- Option 2: The US was not the host for the 2020 dialogue but is actively involved in climate discussions.

- Option 3: The UK co-hosted with Germany in 2021 but not in 2020.

- Option 4: France, another key player, was not the host for 2020.

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