Identify $A$ and $B$ in the following sequence of reaction

Which of the following complex is homoleptic?

In Kjeldahl's method for estimation of nitrogen, $\mathrm{CuSO}_4$ acts as :

Given below are two statements :

Statement (I) : Potassium hydrogen phthalate is a primary standard for standardisation of sodium hydroxide solution.

Statement (II) : In this titration phenolphthalein can be used as indicator.

In the light of the above statements, choose the most appropriate answer from the options given below :