Final answer:
To find images of colonies of Emperor penguins, Lionel should use the search query 'Emperor penguin large group' as it is specific and descriptive.
Step-by-step explanation:
Lionel is looking for images of colonies of Emperor penguins for a school project. The most effective search query to find the results he needs would be c. Emperor penguin large group. This option is specific and descriptive, making it more likely to yield search results of Emperor penguins gathered in colonies. Using just 'Emperor penguins' might show individual penguins or irrelevant information, 'Penguin colony' could include different species of penguins, and 'Emperor penguin family' might only show small groups or individual penguin families.