https://www.reuters.com/article/us-facebook-privacy-britain/facebook-slammed-by-uk-lawmakers-as-cto-promises-transparency-overhaul-idUSKBN1HX1AX >A top Facebook executive apologized for errors made by the firm and vowed to do more to improve transparency during a four-hour grilling on Thursday from British lawmakers who insisted the company's response to a data scandal had been inadequate.