Choice B is the best answer. In lines 39-42("Normally... community"), Akira clarifies that the "matter of urgency" is that he has "an opportunity to go to America, as dentist for Seattle's Japanese community." Akira needs Chie's answer to his marriage proposal so he can decide whether to accept the job in Seattle.
Choices A, C, and D do not provide the best evidence for the answer to the previous question. Choice A is incorrect because in line 39 ("I ... you")Akira apologizes for interrupting Chie's quiet evening. Choice C is incorrect because lines 58-59 ("Depending... hand")address the seriousness of Akira's request, not its urgency. Choice D is incorrect because line 73("My... apologies") shows only that Akira's proposal has "startled" Chie and does not explain why his request is time-sensitive.