1 – Correct
The sentence “…can lower levels of violence…encourages police officers to better regulate their own behaviour”. This suggests that the text assumes that the level of force used by police sometimes exceeds that which is required by the situation.
2 – Wrong
Nothing is mentioned about police departments in different countries so there can be no assumptions made about police departments in different countries.
3 – Correct
The text suggests that the chief reason for body-worn video cameras is that it ensures that the officers issue a clear warning that their interaction is being filmed. Therefore, the text must assume that in cases where public-police interactions have been filmed by bystanders, the individuals involved may not know that they are being filmed.
Since statements 1 and 3 are correct, E is the answer.