Answer:
The correct answer is option a. "lower melting temperature".
Explanation:
Food makers add hydrogen to vegetable oil in order to make them more solid. The melting point of vegetable oils that go trough a partial hydrogenation process do not lower, actually, the melting point increases. Vegetable oils that are partially hydrogenated are partially saturated, which in consequence increases its melting point to the point that they could be solid at room temperature.