Gross billings for merchandise sold by Lang Company to its

customers last year amounted to $13,720,000$; sales returns and

allowances were $370,000,$ sales discounts were $175,000,$ and

freight$-$out was $140,000.$ Net sales last year for Lang Company

were

a$.13,175,000.$

b$.13,720,000.$

c$.13,350,000.$

d$.13,035,000.$

When multiple performance obligations exist in a contract, they

should be accounted for as a single performance obligation when

a$.$ the product is distinct within the contract.

b$.$ all performance obligations are distinct but interdependent.

c$.$ each service is interdependent and interrelated.

d$.$ determination cannot be made.