The correct verb form is "held" because it matches the past tense requirement for the subject "He."
Option (A) "was held" is incorrect because it changes the meaning. "Was held" would imply someone else was holding the child’s hand, rather than the subject "He."
Option (B) "were holding" is also incorrect because it is in the plural form ("were"), which does not match the singular subject "He."
Option (C) "hold" is incorrect because it is in the present tense, which does not fit with the past context.
Thus, the correct sentence is: "He held the child's hand in his."