The correct option is Altocumulus.
Explanation
Clouds are classified primarily based on their altitude and physical form. The World Meteorological Organization (WMO) categorizes clouds into three main levels based on the height of their base above the ground: High clouds, Middle clouds, and Low clouds.
Option Analysis
- Cirrocumulus Cirrocumulus: This is a High cloud (formed at 6,000-12,000 meters). High clouds are indicated by the prefix "Cirro-". They are typically composed of ice crystals.
- Altocumulus Altocumulus: This is a Middle cloud (formed at 2,000-6,000 meters). Middle clouds are indicated by the prefix "Alto-". They often appear as grey or white sheets or layers.
- Stratocumulus Stratocumulus: This is a Low cloud (formed below 2,000 meters). It appears as large, dark, rounded masses, usually in groups, lines, or waves.
- Nimbostratus Nimbostratus: This is a Low cloud (formed below 2,000 meters). It is a thick, dark grey cloud layer associated with continuous rain or snow.
Key Takeaway
Middle clouds are identified by the prefix "Alto-" (e.g., Altostratus, Altocumulus) and are situated between 2 km and 6 km in altitude. High clouds use "Cirro-", and low clouds typically have no specific height prefix or use "Strato-".