When sequencing dna, scientists usually only determine the sequence of one of the two strands. why is this?

In response to framton's dialogue about his health issues, mr. sappleton replies: "no? " said mr. sappleton, in a voice which only replaced a yawn at the last moment. then she suddenly brightened into alert not to what framton was saying. what does this statement reveal about how mrs. sappleton feels about framton? a) she finds him boring. b) she's happy he came by. c) she finds him annoying. d) she feels sorry for him