In linnaeus's time, all living things were grouped into two kingdoms. later, there were five kingdoms, and know we have six kingdoms. what is the main reason for this increase in the number of kingdoms?
scientists have discovered organisms that were previously unknown, so new kingdoms had to be created for them
kingdom plantea had to be split up into several kingdoms when scientists found that not all plants photo synthesize.
as scientists learned more about genetics and biochemistry, some organisms were moved out of existing kingdoms and into new ones.
since the time of linnaeus, what is the main reason for this increase in the number of kingdoms?

a. scientists have discovered organisms that were previously unknown, so new kingdoms had to be created for them
b. kingdom plantea had to be split up into several kingdoms when scientists found that not all plants photo synthesize.
c. as scientists learned more about genetics and biochemistry, some organisms were moved out of existing kingdoms and into new ones.
d. since the time of linnaeus, many new organisms have evolved, and most of them don't fit into the original kingdoms.