What does the underlined 'them' stand for?

What does the underlined 'them' stand for?

The paragraph below comes from Justice by Michael Sandel.

https://books.google.co.kr/books?id=SKEeHVwT5UMC&pg=PA18&dq=%22CEOs+at+major+U.S.+were+paid+344+times%22&hl=en&sa=X&redir_esc=y#v=onepage&q=%22CEOs%20at%20major%20U.S.%20corporations%20were%20paid%20344%20times%22&f=false

In 2007, CEOs at major U.S. corporations were paid 344 times the pay of the average worker. On what grounds, if any, do executives deserve to make that much more than their employees? Most of them work hard and bring talent to their work. But consider this: In 1980, CEOs earned only 42 times what their workers did. Were executives less talented and hardworking in 1980 than they are today?

In this paragraph, I am not so sure about what the underlined 'them' represents.

It seems to be able to refer to 'their employees' based on the prior sentence, but 'CEOs' when considered with the posterior sentence.

I'm in the dark between two choices.

Hope for your replies.