Hello. Which of the following is correct?<br/><br/>a) The number of robots has increased radically in the last four decades, from 2,000 to 250,000 (International Robot Society, 2015).<br/><br/>b) The number of robots increased radically in the last four decades, from 2,000 to 250,000 (International Robot Society, 2015).<br/><br/>Thank you!