Which code in a Visualforce page and/or controller might present a security vulnerability?

Which two approaches optimize test maintenance and support future declarative configuration changes? Choose 2 answers.

How should the developer overcome this problem? While writing a test class that covers an OpportunityLineItem trigger, a Developer is unable to create a standard Pricebook since one already exist in the org.

A company has a custom object named Region. Each Account in Salesforce can only be related to one Region at a time, but this relationship is optional.
Which type of relationship should a developer use to relate an Account to a Region?

What are three characteristics of change set deployments? (Choose three.)