Rivals. Obama and Romney starting trading barbs as rivals this week. In more serious news, Sudan and South Sudan are also sliding closer to confrontation. And in decidedly less serious news, rival N.F.L. front offices are exchanging secrets and innuendo ahead of next week’s draft. There’s no formal rivalry in this week’s quiz, but last week’s average score only improved by two per cent, so let’s see if you can’t at least beat your own marks.