3)dock leaf extract
is not used to neutralise an acid extract because  its a acid i.e.its acidic in nature
but i asked which is 'not' used for that......
oh sorrrrrry
The answer is nettle leaf extract as it is acidic in nature while others are basic and used to neutralize acid extracts.

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Dock leaf extract - it contains oxalic acid and it is used as antacid.
an acid can't be used as an antacid.... isnt it?????
i am sorry, it should be read as "it cannot be used as an antacid". thanks for pointing it out.