The ...... politician thought that all bureaucrats should be polite to him.

The sentence can be understood as an ironic remark on the politician, saying that he expects others to be polite towards him. This would make sense if the adjective showed him not to be polite towards them. 

Docile and Civilised would both show the politician in a good light, which would not fit the ironic tone of the sentence. 

Merciless would mean cruel, which although fits the ironic tone is not the most suitable among the options. 

Insolent means someone rude and arrogant. This would be the best fit, showing the politician to be rude towards others and still expecting others to be polite towards him. 

Therefore, Option A is the correct answer.