The pink color of phenolphthalein in an alkaline medium is due to:

Given below are two statements.
Statement $I:$ In the titration between a strong acid and a weak base,methyl orange is a suitable indicator.
Statement $II:$ For the titration of acetic acid with $NaOH$,phenolphthalein is not a suitable indicator.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which indicator is most suitable for the titration of $0.1 \, N \, Na_2CO_3$ solution with $0.1 \, N \, HCl$?

Methyl orange is an indicator in acid-alkali titration. It gives

The titration curve of a weak acid vs. a strong base with phenolphthalein as an indicator is shown below. The $K_{In} = 4 \times 10^{-10}$. Given: $\log 2 = 0.3$. The number of the following statements which is/are correct about phenolphthalein is $.....$.
$A$. It can be used as an indicator for the titration of a weak acid with a weak base.
$B$. It begins to change colour at $pH = 8.4$.
$C$. It is a weak organic base.
$D$. It is colourless in an acidic medium.

Methyl orange gives $.......$ color in an acidic medium.