The combining form oo means which?

• A. Ovary
• B. Oocyte
• C. Egg
• D. Ovule

Answer: (C)

The combining form oo- signifies egg. In medical and biological terms, oo- is used to refer to egg-related concepts, such as oogenesis (the formation of an egg), oogonium (a cell that gives rise to eggs), and oocyte (an egg cell). Among the options, the direct meaning matched by oo- is “egg,” which is why that choice is the best. The other terms refer to different things: ovary is an organ associated with egg development and is linked to oophor- or ov- roots; ovule is a plant reproductive structure; and an oocyte, while related, denotes a specific egg cell rather than the general concept of an egg.