The passage that was written mainly to inform is:
B
"There are many different kinds of octopuses. Some are as small as 2 inches while some can grow as big as 18 feet. Octopuses have thousands of suckers on their arms that they use to taste and feel."
This passage provides factual information about octopuses, including their sizes and physical characteristics, which fits the purpose of informing the reader. The other passages contain narrative elements, emotions, and storytelling elements that are not primarily focused on providing information.