Correct option is D
Explanation of the Correct Answer: · "We were planning" (past continuous) changes to "had been planning" in indirect speech.
· "Next week" changes to "the following week" in reported speech.
· Thus, the correct sentence is: "They said that they had been planning to visit him the following week."
Why Are the Other Options Incorrect? · (a) "Have been planning" → Incorrect; keeps it in present perfect instead of past perfect continuous.
· (b) "Had planned" → Incorrect; changes past continuous to past perfect, altering meaning.
· (c) "Are planning" → Incorrect; remains in present instead of past.
Thus, the correct answer is (d) "They said that they had been planning to visit him the following week."