Which of the following are immutable once a USD Stage has been opened?

The immutable stage-opening concerns are the path resolver context and the variant fallback configuration used for unselected variants . The resolver context is bound when the stage is created or opened and is used for future asset-path resolution on that stage, regardless of what other resolver context may be bound elsewhere. The OpenUSD UsdStage API documentation describes this binding behavior during stage creation, making option C correct.

Option D is also correct because global variant fallback preferences are defined as preferences “used in new UsdStages.” Once a stage has been composed with its fallback preferences, changing global fallback settings affects newly opened stages, not the already-opened stage’s established fallback behavior.

Option A is incorrect because payload loading is mutable: Load(), Unload(), LoadAndUnload(), and SetLoadRules() modify the stage’s payload working set after opening. Option B is incorrect because layers can be muted and unmuted on an existing stage through MuteLayer(), UnmuteLayer(), and MuteAndUnmuteLayers(). This aligns with Pipeline Development → Stage Opening, Asset Resolution, Variant Fallbacks, Load Rules, and Layer Muting .