# Yield of paddy field can be increased by application of

$\begin{array}{1 1}(A)\;\text{Iron bacteria}\\(B)\;\text{Nostoc}\\(C)\;\text{Archaebacteria}\\(D)\;\text{Symbiotic bacteria}\end{array}$

Yield of paddy field can be increased by application of nostoc
Hence (B) is the correct answer.