The correct answer is C. 100000.
The number of repetitions, which the pavement thickness designed for a given wheel load should be able to support during the life of pavement is 100000. This is based on the AASHTO Guide for Design of Pavement Structures, which is a widely used reference for pavement design. The guide recommends that the pavement thickness be designed to support a minimum of 100000 repetitions of a standard axle load. This number of repetitions is based on the expected traffic volume and the type of pavement being designed.
Option A, 1000, is too low. This number of repetitions would not be sufficient to support the expected traffic volume and the type of pavement being designed.
Option B, 10000, is too high. This number of repetitions would be more than necessary to support the expected traffic volume and the type of pavement being designed.
Option D, 1000000, is also too high. This number of repetitions would be excessive and would not be cost-effective.
Therefore, the correct answer is C. 100000.