Answer: stubbornly resistant to change or new ideas
Step-by-step explanation:
An obstinate person is someone who refuses to change their opinion. Someone who is obstinate is stubborn and hardly listen to others.
Such people are determined to have their own way. Synonyms for obstinate include stubborn, mulish and dogged. Based on the sentences, obstinate means stubbornly resistant to change or new ideas. Peter was rigid and unwilling to change.