Historical Rules · 15 July 2011
Rule 107.1c
Official source text from the 15 July 2011 Rules release
If a rule or ability instructs a player to choose "any number," that player may choose any positive number or zero, unless something (such as damage or counters) is being divided or distributed among "any number" of players and/or objects. In that case, a nonzero number of players and/or objects must be chosen if possible.