To determine the measure of segment \( \overline{IG} \), we need more information about the configuration of points \( I, J, T, U \), the location of point \( G \) (the center of the circle), and the relationships between these points.
However, assuming that \( IU \) and \( IT \) are chords of the circle, and that \( TU = 12 \) denotes a chord length or a distance between two points on the circumference, we still can't derive the exact value of \( IG \) without additional information regarding the placement of \( I \) with respect to points \( T \) and \( U \).
Given the multiple-choice answers provided (3, 4, 5, 6), we could guess based on common values that could arise in symmetrical or specific circle arrangements.
Let's analyze it logically:
- If \( T \) and \( U \) are points on the circle such that \( TU = 12 \), this doesn't directly give us information about \( IG \) unless we know the radius or other distances.
- The distances \( IG \) or chords can hinge upon specific angles if they subtend certain arcs.
If no further context or geometrical properties are available (like symmetry, equal divisions, or a specific angle measure), it is hard to conclude. So typically we might refer to equal divisions generated by specific segments.
Assuming \( IG \) accounts for a division related to angle subtension or equivalent sectors, a common inferring fallback is to consider uniform divisions, leading us to explore operational values.
If \( GI \) is derived related to proportions of the diameter or radii against the context of \( TU \), one can suggest a value of:
- Most reasonable and easily separator being 6.
This being without direct intersections; otherwise is speculative.
Hence, the best approach using contextual clues leads to conclude, but the absolute steadfast value cannot be concluded without more context or geometrically symmetry.
Therefore, please verify against additional information or clarify the circle configuration for an accurate measure. Until then, a testing estimate centers around an outcome of \( 6 \) or other expected average values near \( T, U\).
Final guess: 6