C) powdered sugar in hot water because the sugar is already broken so it would be more faster than sugar cube in hot water
That answer is true. bleh bleh bleh bleh
I believe the answer is 0.016. if i am wrong please tell me if it's wrong. the second option
pH is a symbolic representation of:

and for water we now that:

that means the text give us the information to calculate the concentration of protons and therefore the concentration of ions OH-:

therefore the concentration of OH- can be calculated:

but they are not asking about the concetration of OH- they ask about concentration of Ba(OH)2 and for that we need to know the disolution stechiometry

Whic mean the concentration of Ba(OH)2 is half the concentration of OH-: