The correct option is D C
In the statement “They said they’d phone us until their plane lands” the mistake is in the use of the preposition 'until'. ‘Until’ means to continue an action up to a particular time, i.e. till the plane lands. The given statement means that they will keep calling the speaker till their plane lands, which would be illogical since people are not allowed to use their mobiles while on board. It should ideally be ‘after’ which could mean that they would call after landing. Since there is an error in the third part of the sentence option C is correct, while option D is incorrect. On the other hand, since the first two parts of the sentence don’t contain any error, options A and B are incorrect.