So beautiful As x As beautiful As: Qual é a diferença

Qual a diferença entre "so beautiful as" e "as beautiful as"?

A questão da PUCPR 1998 abaixo, fez surgir essa dúvida. Letra D é a correta.

Choose the only CORRECT alternative to complete the spaces:
I - United States is not ________ as Brazil.
II - The Everest is ________ mountain in the world.
III - Chimpanzees are ________ than dogs.
IV - Aids is ________ disease of human being.
V - Mike Tyson is ________ as Evander Holyfield.

A) as beautiful - the higher - so intelligent - the bad - more strong
B) more beautiful - the most high - as intelligent - the baddest - so strong
C) so beautiful - the high - most intelligent - the badder - stronger
D) so beautiful - the highest - more intelligent - the worst - as strong
E) as beautiful - as highest - more intelligent - the worst - strongest

Obrigada.

Bianca