You will be given a definition of a task first, then some input of the task.
In this task, you will be presented with a question in Dutch language, and you have to write the person names from the question if present. B denotes the first item of a phrase and an I any non-initial word. Phrase used for the person name - PER. There can be instances with no person name entity, then return 'None'.

Toen we hun bloed onderzochten , zagen we dat ze drie keer meer suiker in hun bloed hadden dan andere varkens , zodat ze meer energie hadden om te bewegen en hun spieren zich beter konden ontwikkelen .
Output:
None