Possible answers could be:

• Frank and warm.

• I have always had excellent relationships, and I have been fortunate to be part of egalitarian teams.

• The nature of my work was generally solitary, so my colleagues were my boss, my customers, and my suppliers. My relationships were loyal, honest, and warm. 

• I have excellent relationships with them; there is harmony and sympathy for one another.
• Excellent. In the type of work I do, I could not operate without their support and confidence.