Which adjective describes speech or writing that is clear and easy to understand?

The adjective "lucid" is used to describe speech or writing that is clear and easy to understand. When something is termed as lucid, it suggests that the ideas are expressed in a straightforward manner, making them accessible to the audience. Lucid language is often characterized by its clarity, lack of ambiguity, and effective communication of complex thoughts in a way that is easily comprehensible.

In the context of the other options, "inquisitive" refers to a desire for knowledge or information and doesn't pertain to clarity. "Goad" is a verb that means to provoke or annoy someone so as to stimulate some action or reaction; it does not describe clarity of expression. "Euphemism" refers to a mild or indirect word or expression substituted for one considered to be too harsh or blunt, which indicates a lack of straightforwardness rather than clarity. Therefore, "lucid" is the most fitting choice for describing clear and easy-to-understand speech or writing.