user: Question: Which source has a Cost Free, and an Activity of Some, and an Editor of Markitup?
Columns: ['Editor', 'Site', 'Style, clone of', 'Cost ( US$ )', 'Open source', 'Activity']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Ace (editor)', 'Home, demo', 'Sublime Text / Microsoft Visual Studio', 'Free', 'Yes', 'Yes']
SQL:

assistant: SELECT "Open source" FROM "Table" WHERE "Cost ( US$ )" = 'Free' AND "Activity" = 'Some' AND "Editor" = 'Markitup';