Why an IMU alone cannot be trusted for long

You are given a robot with only a 6-DOF IMU (3-axis accelerometer + 3-axis gyroscope) and asked to estimate its position and orientation over a 10-minute mission. Explain why integrating the IMU alone leads to large errors. In your answer, distinguish between (a) deterministic errors like bias and scale factor, and (b) stochastic errors (white noise / random walk), and describe how each propagates when you integrate gyro rate to get angle and accelerometer specific force to get position. Then state what you would add to bound the drift and why.