In the 4th option (they ....one) we can use...have to instead of had to .....also right experts??? But is that had to right ???

Dear Student,
Given below is the answer to your question.

Both they have to and had to are correct. Only the tense changes in both the case.

They have to is present. (They have to take the baby to the doctor because she is sick)
They had to is past ( They had to take the baby to the doctor because she was sick)

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