In typical versions of this question, the athlete workout table shows things like:

Distances recorded sometimes in miles, sometimes in kilometers, or

Times recorded in different formats (e.g., 00:35:10 vs 35.1 vs 35min), or

Mixed conventions that make direct comparison difficult.

This is a classic data inconsistency issue:

The same field/attribute (e.g., distance, time) does not follow a consistent unit, format, or coding scheme across rows.

Even if each individual value might be “possible,” they are not standardized to the same convention.

Why the other options are less appropriate:

Duplicate data (A): Would mean repeated identical rows or values; not the case here.

Data outlier (B): Refers to extreme values that still follow the same measurement and format but are numerically unusual; here the problem is the inconsistent representation, not just extremity.

Invalid data (D): Would mean values that violate business rules or allowed ranges (e.g., negative distance); here, the focus is on differences in units/format, which aligns more with inconsistency.

Thus, the best description of the issue is Data inconsistency (C).

CompTIA Data+ Reference (concept alignment):

DA0-001 Objectives – Data quality: consistency as a dimension (same units, formats, and definitions across records).

Study coverage of inconsistent units and formats as a data quality problem.