Answer:
a. Olfactory white
Step-by-step explanation:
Olfactory White -
It is the smell which is made up of many of the strong and diversified smell ( more than 30 smells ) , is known as the olfactory white .
Human beings have when smell this mixture of smells across a large range can not distinguish between these smells , and the components can not be distinguished .
The smell of the Olfactory white is nor bad or any good .
The concept is very much same as the different colors of rainbow , when combined make a white color .