How about E) I understand and use GNU Parallel and also completely disagree with the author's insistence that citing tools is appropriate. Even in your second

How about E) I understand and use GNU Parallel and also completely disagree with the author's insistence that citing tools is appropriate. Even in your second link, almost everything listed are papers about Parallel itself. If I was writing about Parallel, I'd be fine with citing it. If instead it's the means to another end, I wouldn't.