Implicit block passing and dynamically defined methods

Please consider the following different ways to define method m:

• Method 1:

  class C
    def m; yield; end
  end
  

• Method 2:

  class C
    def initialize
      (class << self; self; end).class_eval do            
        define_method(:m){|&b| b.call }
      end
    end
  end
  

• Method 3:

  class C
    def initialize
      (class << self; self; end).class_eval do            
        define_method(:m){puts block_given?; yield}            
      end
    end
  end
  

Then I can invoke m using Object#send.

o = C.new
o.send(:m) {puts 'test'}

While calling m using Method 1 or Method 2 works fine, Method 3 gives this error:

no block given (yield) (LocalJumpError)

I understand that a block is not an object, but instead just a part of method calling syntax and you cannot pass an implicit block from one function to another without writing something obscure like this:

def printer
  yield
end
def proxy
  printer &Proc.new
end

proxy { puts "&Proc.new probably creates Proc object from block"}

But in that case, why does Method 1 work? It would be awesome to get an answer which would explain what's happening under the hood.