Which of the following prefixes means 'blue'?

The prefix "cyano" originates from the Greek word "kyanos," which translates to "dark blue." It is commonly used in scientific terminology, especially in fields like biology and chemistry, to denote blue pigments or compounds. For example, cyanobacteria are often referred to as "blue-green algae" due to their blue coloration. Understanding prefixes helps to decipher complex terms and their meanings in various scientific contexts, thus "cyano" is the correct choice for indicating something related to blue.

The other prefixes have distinct meanings: "cirro" refers to high, wispy clouds; "chloro" means green, often associated with chlorophyll in plants; and "melano" relates to black or dark pigments, often seen in terms linked to skin color or melanin. Each of these prefixes indicates different colors, which helps clarify their specific applications in scientific vocabulary.