Which of the following statements about job order cost systems is true?

a$.$ Examples of companies that often use job order cost systems are oil refineries, paper producers, chemical processors, and food processors.

b$.$ Job order cost systems are often used by companies that manufacture units of a product that are indistinguishable from each other.

c$.$ Job order cost systems are often used by companies that manufacture products using a continuous production process.

d$.$ Job order cost systems are often used by companies that manufacture custom products for customers or batches of similar products