Simple multicellularity has evolved independently in at least 25 lineages, whereas complex multicellularity has only evolved in a select few. Which of the following BEST supports this observation?

a. complex multicellularity requires fewer evolutionary steps to achieve than simple multicellularity
b. bulk flow requires cells to tolerate crowding conditions such as elevated concentration of waste
c. elements necessary for coordinated multicellularity are present in some single-celled organisms
d. simple multicellularity requires fewer evolutionary steps to achieve than complex multicellularity

Evolution is the change in the characteristic of the organisms with the time. This change might occur depending on the external habitat of the organisms and their adaptation towards the environment.

The simple organism has the ability to evolve more rapidly than the complex organisms and do not require more steps to change themselves into the multi cellular organisms. They require less time for evolution than multicellular organisms and has the ability to show higher lineages than the multicellular organisms.

Thus, the answer is option (D).