LEFT(Account.Zip_Code_c, 5) is the correct formula to display only the first five digits of Zip Code from the parent Account. LEFT function returns the specified number of characters from the left side of a text string.
Account.Zip_Code_c is the custom text field that stores the Zip Code on Account object. 5 is the number of characters to return from the left side of the Zip Code. The other options are not valid formulas or functions.

To ensure that only the sales reps and their manager's executive can view the rep's evaluation record but the reps should not be able to view the executive comment field on their review, a private sharing model granting record access using hierarchy and field-level security should be used. A private sharing model means that only the owner of a record and users above them in the role hierarchy can view the record by default. Record access can be granted to other users using manual sharing, sharing rules, or Apex sharing. Field-level security controls which fields are visible or editable for different profiles or permission sets.

The best solution to create a report to compare the number of support cases in each status and by priority is to use grouping. Grouping allows the app builder to summarize data by one or more fields, such as status and priority, and display them in rows and columns. Grouping also enables the app builder to use different chart types, such as stacked bar charts or matrix charts, to visualize the data. Bucket columns are not a suitable solution, as they are used to categorize data into predefined groups, such as high, medium, or low. Custom report types are not a suitable solution, as they are used to define the objects and fields available for a report, not how to display them. Filters are not a suitable solution, as they are used to limit the data shown in a report based on certain criteria, not how to compare them

Setting email deliverability to no access would prevent outbound email sends during testing in a sandbox.
This would ensure that no emails are sent to any users or external email addresses from the sandbox. Setting email deliverability to system email only would still allow some emails to be sent, such as password reset emails or new user emails. Configuring SMTP authentication or email relay would not affect email deliverability in a sandbox

A permission set containing the salary record type and assigning it to the appropriate users would allow only those users to create salary applicant records, while still allowing all users to view all applicant records. This is the most granular and flexible way to meet the requirement