What type of language is commonly used in everyday conversation?

Natural language is the correct answer because it refers to the language that humans use in everyday communication. This includes languages like English, Spanish, Mandarin, and many others, which are characterized by their potential for nuance, emotional expression, and a vast vocabulary related to a wide array of ideas and experiences.

In contrast, programming languages are specifically designed for writing software and have strict syntax and rules that do not accommodate the flexibility or expressiveness of natural language. Semi-formal languages apply a structure or protocol to communication while still retaining some elements of natural language, but they are not commonly used in typical conversation. Graphical languages involve visual representations and symbols rather than spoken or written text, which also does not fit the context of everyday human interaction.