One of the Disadvantages of Proprietary Software Is That

One of the disadvantages of proprietary software is that:

A) it is hard to control results even if one is involved in the development of software.
B) it is difficult to achieve what is required in terms of features and reports.
C) it does not allow modification of features
That one might need to counteract an initiative by competitors.
D) it can take a long time and significant resources to develop the required software features.