Concept:The expression “it is high time” is followed by a past tense verb to show that an action should happen now.Explanation:The required pattern is: “It is high time + subject + past verb.”Here, the past verb of “start eating” is “started eating.”So the correct sentence is: “Isn’t it high time we started eating?”This past form is not about past time; it is a special subjunctive-like structure used to express urgency.Hence, options B, C, and D do not fit the required pattern.Answer:A. started eating