Which definition best suits the term "precarious"?

The term "precarious" refers to a situation or condition that is unstable, risky, or uncertain, often involving a lack of security or safety. When something is described as precarious, it typically indicates that it can easily shift or fail, leading to dangerous or undesirable outcomes. Therefore, "affording no reassurance and dangerously insecure" is the most fitting definition, as it encapsulates the essence of the term, emphasizing the inherent instability and risk involved.

The other options do not align with the meaning of "precarious." For example, describing a situation as "secure and reliable" completely contrasts with the idea of precariousness, which embodies uncertainty. Similarly, being "full of excessive detail" or "living easily without worry" suggests a state of comfort and stability, which is at odds with the precarious nature of being at risk or in a vulnerable position.