Clouds are grouped by their height and shape, and only a couple of types are actually built to release steady rainfall, so this question is really asking you to spot the "rain cloud" among four look-alikes.
- Nimbostratus: This is the thick, dark grey blanket cloud that covers the whole sky and drops slow, steady rain or snow for hours, exactly what the word "nimbo" (rain bearing) signals in cloud names.
- Altocumulus: A mid level cloud of small white or grey clumps, it can hint that weather is changing but it does not itself pour down rain.
- Cirrostratus: A thin, high, ice crystal sheet that often produces a ring or halo around the sun, linked with calm or slowly worsening weather, not rainfall.
- Stratocumulus: A low, patchy, lumpy grey layer that mostly gives a dull overcast sky, with at most a light drizzle rather than real rain.
Among these four, only nimbostratus is built to drop continuous rain over a wide area, which matches exactly what the word "rain bearing cloud" describes.
Let's summarize:
- The "nimbo" or "nimbus" root in a cloud's name marks it as a true rain producer.
- Altocumulus, cirrostratus and stratocumulus do not fit that description.
So option 1, nimbostratus, is the correct rain bearing cloud.