Identify the sphere which does not form a biosphere-

The correct answer is Option (1) → Chromosphere

The biosphere is the narrow zone where life exists, and it is formed where the three physical realms of the earth meet — the lithosphere (land), the hydrosphere (water) and the atmosphere (air).

The chromosphere has nothing to do with the earth at all: it is a layer of the Sun’s atmosphere lying above the photosphere, visible as a red rim during a total solar eclipse.