The two factors that are most likely to affect whether a galaxy will evolve by merging with a second galaxy are:
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its size compared to that of the other galaxy - Larger galaxies have a stronger gravitational pull and are more likely to attract smaller galaxies, leading to mergers.
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its distance from the other galaxy - The gravitational influence between galaxies decreases with distance, so galaxies that are closer together have a higher likelihood of merging.
Therefore, the correct answers are "its size compared to that of the other galaxy" and "its distance from the other galaxy."