Which adjective best describes something that is obvious?

The adjective that best describes something that is obvious is "apparent." This term specifically conveys that something is easily understood or recognized without needing much thought or clarification. When something is apparent, it is readily observable and does not require additional explanation to make it understood.

While "conspicuous" suggests that something stands out and is easily noticed, it carries a connotation of attracting attention, not necessarily that it is clear or obvious. "Clear" implies a lack of ambiguity or confusion but does not inherently indicate that the information is readily observable or undeniable, which is central to the notion of obviousness. "Visible" simply means that something can be seen but does not imply that it is understood or evident without further information.

Therefore, "apparent" captures the essence of something being obvious more accurately than the other adjectives provided.