Phenolphthalein is not suitable for the titration of

Phenolphthalein is not a good indicator for titrating:

$50 \ mL$ of $0.1 \ M$ of a weak acid $HA$ is titrated with $0.1 \ M$ of $NaOH$. The ionization constant of $HA$ $(K_a)$ is $1.8 \times 10^{-5}$. Using the given information and from the options shown below,the best indicator for the titration of $HA$ with $NaOH$ is $....$

In an acid-base titration,the rapid change in $pH$ near the equivalence point depends on the indicator used. The $pH$ of the solution is related to the ratio of the concentrations of the conjugate acid $(HIn)$ and base $(In^-)$ forms of the indicator by which equation?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Phenolphthalein is a $pH$ dependent indicator,remains colourless in acidic solution and gives pink colour in basic medium.
Reason $R$: Phenolphthalein is a weak acid. It doesn't dissociate in basic medium.
In the light of the above statements,choose the most appropriate answer from the options given below.

The best indicator for the detection of the end point in the titration of a weak acid and a strong base is: