Choice D is the best answer. In lines 24-25("I so pressingly urge a strict observance of all the laws"), Lincoln says, "I so pressingly urge a strict observance of all the laws." In this context, the word "urge" most nearly means advocate, because when Lincoln urges people to obey the laws, he is pleading in favor of them doing so.
Choices A and C are incorrect because in the context of lines 24-25 ("I so pressingly urge a strict observance of all the laws"), to urge that laws be followed is to advocate for them to be obeyed, not to speed up such adherence (choice A) or make such adherence necessary (choice C). Choice B is incorrect because Lincoln is asking people to follow the laws but not directly causing people to obey them.