How many of the following statements is/are correct?

(1) Both Rhizobium and Frankia are free-living in soil and can fix ${\mathrm{N}}_2$ only under symbiotic condition.

(2) Root nodules can be best observed before flowering

(3) The formation of root nodules takes place as a result of the division of cortical and pericycle cells.

(4) When Rhizobium is free living it is aerobic but when it is symbiont it becomes anaerobic to protect Mo-Fe protein. Options :

(1) 4

(2) 3

(3) 2

(4) 1