单项选择题

It is pretty much a one-way street. While it may be common for university researchers to try their luck in the commercial world, there is very little traffic in the opposite direction. Pay has always been the biggest deterrent, as people with families often feel they cannot afford the drop in salary when moving to a university job. For some industrial scientists, however, the attractions of academia (学术界) outweigh any financial considerations.
Helen Lee took a 70% cut in salary when she moved from a senior post in Abbott Laboratories to a medical department at the University of Cambridge. Her main reason for returning to academia mid-career was to take advantage of the greater freedom to choose research questions. Some areas of inquiry have few prospects of a commercial return, and Lee’s is one of them.
The impact of a salary cut is probably less severe for a scientist in the early stages of a career. Guy Grant, now a research associate at the Unilever Centre for Molecular Informatics at the University of Cambridge, spent two years working for a pharmaceutical (制药的) company before returning to university as a post-doctoral researcher. He took a 30% salary cut but felt it worthwhile for the greater intellectual opportunities.
Higher up the ladder, where a pay cut is usually more significant, the demand for scientists with a wealth of experience in industry is forcing universities to make the transition (转换) to academia more attractive, according to Lee. Industrial scientists tend to receive training that academics do not, such as how to build a multidisciplinary team, manage budgets and negotiate contracts. They are also well placed to bring something extra to the teaching side of an academic role that will help students get a job when they graduate, says Lee, perhaps experience in manufacturing practice or product development. "Only a small number of undergraduates will continue in an academic career. So someone leaving university who already has the skills needed to work in an industrial lab has far more potential in the job market than someone who has spent all their time on a narrow research project." By "a one-way street" (Line 1, Para. 1), the author means ______.