Answer:
spirogyra
Step-by-step explanation:
Spirogyra is most likely to be found along roadsides in ditches and ponds because they are cosmopolitan and widely distributed in various fresh water bodies in the environment.
Although all the three organisms belongs to the green algae, both protococcus and cladophora do not have the distribution of spirogyra in the environment. Hence, there is a higher probability of finding spirogyra than the remaining two species.