Task: Question Answering
Input (English): Background Paragraph: Parallel slowdown is a phenomenon in parallel computing where parallelization of a parallel algorithm beyond a certain point causes the program to run slower (take more time to run to completion).[1]

Parallel slowdown is typically the result of a communications bottleneck. As more processor nodes are added, each processing node spends progressively more time doing communication than useful processing. At some point, the communications overhead created by adding another processing node surpasses the increased processing power that node provides, and parallel slowdown occurs. 
Story: John landed a job as an IT manager. His boss asked him to figure out problems in two similar programs, program A and program B. John found program A having parallel slowdown, but program B does not have parallel slowdown. He has to weigh the merits of using these programs. 
Question: Which program does not have issue with communication bottleneck, program A or program B?
Output (English): program B.