"The reason that" or "The reason why"

Are all three versions correct usage? Is one preferred?

The reason why students did not score high on this test is...

The reason that students did not score high on this test is..

The reason students did not score high on this test is...

[Anglika]

All are acceptable and used.

[BobK]

But beware: 'The reason why...is because...' is used but I wouldn't call it 'acceptable'.

b

[kiranlegend]

Bob, you wouldn't call it acceptable? So that means the first version is not recommended to use?

[svartnik]

Originally Posted by kiranlegend

Bob, you wouldn't call it acceptable? So that means the first version is not recommended to use?

It is okay, except if the word 'because' raises its ugly head in it.

[engee30]

http://www.usingenglish.com/forum/280341-post15.html

[abaka]

"Theirs not to reason why, theirs but to do and die."

Obviously this is not the same grammatical usage, but I wonder what part of the persistence of "the reason why is" we can thank Tennyson for.

[kiranlegend]

who is Tennyson?:o

[bhaisahab]

Alfred Lord Tennyson was an English poet who wrote, among many other things, the lines quoted by abaka.

[bhaisahab]

As Anglika has said all are used, but it is best to avoid this; The reason why students did not score high on this test is... because there will always be people who will criticize it's use.