Mark the letter A, B, C, or D to indicate the sentence that is closest in meaning to each of the following questions.
"Let’s go for a walk. We 've been working all day,” said Joanna.
A. Joanna suggested going for a walk because they had been working all day.
B. Joanna insisted on going for a walk because they had been working all day.
C. Joanna suggested going for a walk because they have been working all day.
D. Joanna suggested going for a walk because she had been working all day.