Cluster bean contains mucilaginous substance is

Answer: Option A

Cluster bean commonly known as guar has come to be recognized as one of the most important commercial crops of arid and semi-arid regions. It is a drought-hardy leguminous crop because of its deep tap rooting system and has a high capacity to recover from water stress.
Cluster bean contains a mucilaginous substance that is Mannogalacton. The seed of cluster bean contains about 30 - 33% gum in the endosperm. The discovery of the Mannogalacton gum in the endosperm in 1948, led to this hitherto insignificant plant gaining importance as an industrial crop.