How to Prove or disprove a complete sufficient statistic : Statistics Tutorial

The random variable X takes the values ,1,2 according to a probability distribution.
Determine whether the distribution of X is complete or not. (question 6.19 Casella & Berger Statistical Inference)
In this question , there is only one observation. So we are going to prove whether that observation is complete or not based on the definition of the complete sufficient statistic