Which fields in a table are required fields by definition? Select one: a. A field with a default value b. A field with a primary key c. A field with a lookup List. d. A field with an input mask functions refers to using one function within another one. Select one: a. Nesting b. IIF c. Math d. IsNull A primary key: Select one: a. must include letters. b. must contain a unique value for each record within a table. c. has the same value for all records in a relational database. d. is a unique record within a relational database. is the first method for controlling data input in a field of a table. Select one: a. Creating a data macro b. Creating an appropriate validation rule c. Creating an appropriate default value d. Selecting an appropriate data type Sum, Avg, and Max are examples of functions that are used to evaluate entire columns of data. Select one: a. compound b. aggregate c. number d. summary