Explanation
According to this source, if an object is set to Controlled by Parent in its organization-wide default settings, then access to its records is determined by the parent record. In this case, since Case object has View All permission for service reps, they will be able to access all contact records related to those cases, regardless of their ownership or sharing rules. However, they will not be able to access all account records, since account object has Private OWD and no other sharing mechanism is mentioned. The other options are not correct.

Explanation
Two platform features that can be used to support the requirements for granting access to Job records are
"View All" profile settings and manual sharing. The "View All" profile setting can be enabled for the Delivery profile to grant them View access to all Job records regardless of ownership or role hierarchy. The manual sharing feature can be used by the Delivery user who owns a job to grant access to a Product Development user on a case-by-case basis

Explanation
The action that Mary can take on Joe's Invoice records is none. This is because Mary's profile does not have the Read permission for the Invoice object, which means she cannot view any Invoice records, regardless of the OWD or role hierarchy settings. Profile permissions override any other access settings3. Read/Write, Edit Only, and View Only are not possible actions for Mary.

Explanation
The correct security settings to achieve this are to set all Organization-Wide Default security to be Private for both internal and external users and use Sharing Rules to grant the desired access. This way, internal users can access all survey responses through the account object, and external users can only access survey responses that belong to their own account through the custom object.