Rephrase with C - In no other election did Obama cause such a sensation as (he did) in his presidential race of 2008. (We can omit 'he did' and still convey the same meaning) Sensation caused by Obama in all the previous elections is compared with sensation caused by Obama in presidential race.) In no other historical sighting did Halley's comet cause such a worldwide sensation as (it did) in its return of 1910-1911
Rephrase with A - In no other election did Obama cause such a sensation as did his presidential race of 2008. ( Incorrect comparison. Sensation caused by Obama in all the previous elections is compared incorrectly with sensation caused by presidential election. But we should compare sensations caused by Obama in both the cases.) In no other historical sighting did Halley's comet cause such a worldwide sensation as (did its return in 1910-1911)