제가 외국에서 나온 토익교재로 공부중인데

we found that the width of the mounting brackets to be almost 8 inches longer than we had _____ in our design specifications .

a) noted
b) informed
c) talked
d) spoken

여기서 제가 답을b로 했는데 a가 답이더군요
그래서 해설을 보니

(a) correct. noted is the past participle and is the most appropriate word in this context.

(b) informed would need to be followed by you about.

(c) talked would need to be followed by to you about but would not be appropriate because the design specifications were most likely put in writing.

(d) spoken would need to be followed by about but would not be appropriate because the design specifications were most likely put in writing.

라고 되어 있습니다. 여기서 각 해설마다 있는 by뒤에 있는 you about이나 about을 어떻게 해석해야 할지
모르겠습니다..ㅠㅠ

해설지 해석 좀 도와주세요ㅠ