CORRECT ANSWER IS -
C: Master Detail

Explanation Why Correct:
C: A Master-Detail relationship is the correct choice because it allows for tight control over the access to child records (Line Items) based on the parent record's (Order) access. If a user does not have access to the master record, they cannot access the detail records. This relationship type supports the requirement that financial representatives can see the Order information but not the Line Items.

INCORRECT OPTIONS:
A: This is not correct as an Indirect Lookup relationship is used to relate a child external object to a parent standard or custom object, which is not the case here.
B: A Lookup relationship does not provide the same level of access control as a Master-Detail relationship, so financial representatives could potentially see Line Items if given access to them.
D: Direct Lookup is not a standard Salesforce relationship type.

Correct Answer is B Lookup