The correct option is A Lingha pearl
The best quality of pearl is known as Lingha pearl obtained from marine oysters. The duration of formation of pearl is about 7 years. The pearl oyster belongs to genus Pinctada, family pteriidae, and class bivalvia and phylum mollusca. The important species producing good quality of pearl are Pinctada vulgaris (schumachar), Pinctada marigavitifera (Linn), Pinctada chemnitzi (Philippi), Pinctada anamioides (Reeve) and Pinctada alropurpurea (Dunker). All these species are marine and it is the marine forms which produce the pearl of fine quality.