According to the Nexus Guide1, the Nexus Sprint Review is an event where the Nexus presents the Done Integrated Increment that was built over the Sprint and collects feedback from the stakeholders. The Integrated Increment is the combined work of all the Scrum Teams in the Nexus that meets the Definition of Done. The Nexus Guide also states that the Nexus Integration Team is a specialized Scrum Team that provides services and guidance to the Scrum Teams in the Nexus to ensure that the Integrated Increment is produced every Sprint.

In the scenario, the teams are not using a shared environment, which implies that they are not integrating their work frequently and effectively. This means that there is no single Integrated Increment that can be inspected and adapted by the stakeholders. This also suggests that the Nexus Integration Team is lacking or nonexistent, or that it is not fulfilling its role of facilitating integration and resolving dependencies. Without a Nexus Integration Team and a shared environment, the Nexus cannot deliver a valuable product Increment that meets the Product Goal.

The Sprint length and the integration phase are not relevant to the scenario. The Sprint length is determined by the Nexus based on the complexity and uncertainty of the product, and it should be less than a month. The integration phase is not a separate phase in Nexus, but a continuous activity that happens throughout the Sprint. Therefore, A and B are not correct answers.