Does the pH increase or decrease with each of the following additions? To what extent?

$($a$)5$ drops of $0\mathrm{.}1$ M NaOH added to $100$ mL of $0\mathrm{.}5$ M acetate buffer:

decreases to a small extent

decreases to a large extent

increases to a small extent

increases to a large extent

$($b$)5$ drops of $0\mathrm{.}1$ M HCl added to $100$ mL of $0\mathrm{.}5$ M acetate buffer:

decreases to a large extent

decreases to a small extent

increases to a large extent

increases to a small extent

$($c$)5$ drops of $0\mathrm{.}1$ M NaOH added to $100$ mL of $0\mathrm{.}5$ M HCl:

decreases to a small extent

decreases to a large extent

increases to a small extent

increases to a large extent

$($d$)5$ drops of $0\mathrm{.}1$ M NaOH added to distilled water:

increases to a large extent

decreases to a large extent

increases to a small extent

decreases to a small extent