Which of the following is a flowering plant with nodules containing filamentous nitrogen-fixing micro-organism

Casuarina equisetifolia is a flowering plant (angiosperm), although its needle-like branchlets with scale leaves make it look like a pine; it is often called the Australian pine, she-oak or horsetail tree.
Its roots bear nodules that contain Frankia, a filamentous nitrogen-fixing actinomycete.
So it is a flowering plant with nodules containing a filamentous nitrogen-fixing micro-organism.
Crotalaria juncea (sunn hemp) and Cicer arietinum (gram) are legumes; their root nodules contain Rhizobium, which is a rod-shaped bacterium and not filamentous.
Cycas revoluta has coralloid roots containing the filamentous cyanobacteria Anabaena and Nostoc, but Cycas is a gymnosperm and not a flowering plant.
So the answer is Casuarina equisetifolia.