Macrobrachium rosenbergii belongs to the class:

Correct option is B

Correct Answer: (b) Malacostraca
Explanation:
→ Taxonomically, M. rosenbergii is in Class Malacostraca (largest class of crustaceans). Order is Decapoda and family Palaemonidae.
→ Malacostraca includes crabs, lobsters, shrimps and prawns.
Information Booster:
→ Correct hierarchical sequence: Phylum Arthropoda → Subphylum Crustacea → Class Malacostraca → Order Decapoda.
Additional Information (Other Options):
(a) Decapoda is the order (not class).
(c) Palaemonida/Palaemonidae refer to infraorder/family depending on classification.
(d) Maxillopoda is a different crustacean class (e.g., barnacles, copepods).