Franklin Corp. sells, installs and services telephone systems to businesses. Franklin includes two years of customer training and support as part of its sales contract. In a contract with a new customer who pays in full at the time of equipment installation, when would franklin recognize revenue for the work under US GAAP?

A. When the equipment is installed, if subsequent training and support are included in the contracted sales price

B. At the end of two years, when all services have been completed

c. Proportionately as separate contract elements are performed

D. When the price becomes fixed and collection is reasonably ensured