1. **Problem Statement:**
Pentagon EFGHI is rotated 180° clockwise about point I to form pentagon E'F'G'H'I'. We need to determine which line segment is parallel to TH'.
2. **Understanding Rotation:**
A 180° rotation about a point means every point is rotated half a turn around that point. The image of a point P after rotation about I is such that I is the midpoint of segment PP'.
3. **Key Insight:**
Since the rotation is about point I, point I remains fixed. The segment TH' connects point T (which is not a vertex of the pentagon, but presumably a point related to the figure) to H' (the image of H after rotation).
4. **Analyzing the Options:**
- a) EI: segment from E to I
- b) GH: segment from G to H
- c) TE': segment from T to E' (image of E after rotation)
5. **Rotation Properties:**
- The segment GH will rotate to G'H'.
- The segment EI will rotate to E'I'.
- Since I is the center, EI and E'I' are collinear and opposite directions.
6. **Determining Parallelism:**
- TH' is a segment involving H' (rotated H) and T.
- TE' involves E' (rotated E) and T.
7. **Conclusion:**
Because rotation preserves angles and parallelism, the segment TE' will be parallel to TH' after rotation.
**Final answer:** c) TE'
Rotation Parallel
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