The correct option is
C transitive
If R1 and R2 are transitive on a set A, then R1∪R2 may or may not be transitive. As an example, consider the set A=1,2,3
Let R1=(1,1),(2,2),(3,3),(1,2),(2,1)
and R2=(1,1),(2,2),(3,3),(1,3),(3,1) then the R1 and R2 are equivalence relations on A. However,
R1∪R2=(1,1),(2,2),(3,3),(1,2),(2,1)(1,3),(3,1)is not transitive as (2,1) and (1,3)∈R1∪R2 but (2,3)∉R1∪R2