**Core Concept**
Temporal relationship is a fundamental principle of causal association, which involves a temporal sequence between the exposure and the outcome. In a causal relationship, the exposure must precede the outcome. Additionally, consistency and specificity are also essential characteristics of causal association.

**Why the Correct Answer is Right**
Causal association requires a clear temporal relationship between the exposure and the outcome. This means that the exposure must precede the outcome, and the outcome must not occur unless the exposure is present. In a temporal relationship, the exposure is often the cause, and the outcome is the effect.

**Why Each Wrong Option is Incorrect**
**Option A:** Temporal relationship is indeed a characteristic of causal association, as it establishes a sequence between the exposure and the outcome.
**Option B:** Consistency is also a characteristic of causal association, as it involves the consistent occurrence of the outcome following the exposure across different populations and studies.
**Option C:** Specificity is another characteristic of causal association, as it involves a clear and direct relationship between the exposure and the outcome, with minimal or no overlap with other potential causes.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that a temporal relationship is a necessary but not sufficient condition for establishing a causal association. Other characteristics, such as consistency, specificity, and biological plausibility, must also be present to confirm a causal relationship.

**Correct Answer: D.**