The correct option is C Assertion is true but the reason is false
Commensalism is a type of interspecific interaction in which, out of the two interacting species, one is benefited and the other is neither benefited or harmed.
The organism that gets benefitted is called commensal and the organism that does not derive any benefit nor gets harmed is called a host. ‘+’ sign is used to represent commensal and ‘0’ sign is used to represent the host.
Some orchids grow as epiphytes on the branches of a mango tree. Epiphytes are plants that grow upon other plants only for support.
In this case orchids are commensal organisms as they benefit from the mango tree as it provides support. The mango tree is host and it is neither benefited or harmed from this interaction.
Mutualism is a type of population interaction in which both interacting species are mutually benefited.
Hence, the assertion is true and the reason is false.