In a Tools Rental Business, a Form Is Used to Reserve

In a tools rental business, a form is used to reserve large construction tools for customers (i.e. subcontractors working for a construction company) . The following fields appear on the form:
(tool information)
Item#
Type
Descr
Size
Cost/Day
Mfg (Tool manufacturer)
MfgAddr (Manufacturer address)
Mfg phone
(Customer and reservation information)
rental# (rental order number for the tool, unique for a given tool)
CustId
CustName
CustAddress
CustPhone
Checkout_date (future date for a future reservation or past date for a current rental)
Days (Expected length of rental)
ConsName (Construction Company Name)
ConsAddr (Construction Company Address)
Discount (specific to a construction company)


-Which form field does not belong to the child node?

A) CustId
B) Discount
C) MfgAddr
D) Item#