A student used a pipette to add 25.0 cm of KOH of unknown concentration to a conical flask.
The student carried out a titration experiment to find the volume of 0.150 mol/dmº
H2SO4 needed to neutralise the KOH.
The student found that, on average, 17.20 cm of the H2SO4 solution was
required for neutralisation.

Calculate the concentration of the KOH solution.

The concentration of the KOH solution = 0.2064 M

Titration is a procedure for determining the concentration of a solution (analyte) by reacting with another solution whose known concentration (usually a standard solution) is called the titrant. Determination of the endpoint/equivalence point of the reaction can use indicators according to the appropriate pH range  

Acid-base titration formula  

Ma Va. na = Mb. Vb. nb  

Ma, Mb = acid base concentration  

Va, Vb = acid base volume  

na, nb = acid base valence  (number of ions H+/OH-)

a=H₂SO4(valence = 2, H₂SO4⇒2H⁺+SO₄²⁻, 2 ions H⁺)

b=KOH(valence = 1, KOH⇒K⁺+OH⁻, 1 ion OH⁻)

Ma = 0.15 M

Va = 17.2 cm³

Vb=25 cm³

The concentration of the KOH(Mb) :

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a