Question

merges all visible layers into a single background layer and discards all hidden layers.
hide
flattening
layer merging
mask

Explanation:

Flattening in image - editing software merges all visible layers into a single background layer and discards hidden layers. Hide only conceals a layer, layer - merging may not discard hidden layers, and a mask is used for non - destructive editing to reveal or hide parts of a layer.

Answer:

B. Flattening