If a comet were so large that its mass generated more gravity, it would likely become more similar to a celestial body like an asteroid or even a planet, depending on its size. Larger bodies tend to have stronger gravitational forces, which can lead to different physical characteristics, including a lack of a prominent coma or tail. This is because a strong gravitational pull can keep the volatile materials contained, preventing them from escaping and forming a coma or tail as the comet approaches the Sun.
Among the provided options, the most accurate response would be "It wouldn’t have a tail." This is because a larger mass could mean that the comet's gravity would prevent the outgassing material from forming the typical features seen in comets as they approach the Sun.