$pH$ scale was introduced by
A. SorenSen
B. Newton
C. Chadwick
D. Roentgen

Hint: It is known to us that $pH$ is scale or a method used to identify the acidity and basicity of different solutions. The $pH$ scale is having a range from one to fourteen. The acidic solutions have a value near one. The solutions with low $pH$ value are acidic while when the $pH$ value is high is basic in nature.

Complete Step by step answer:It was made $110$ years ago, experiments with beer at the famous Carlsberg research lab in Copenhagen, Søren Peter Lauritz Sørensen develops the pH scale, which identifies whether a substance is acidic or basic in nature.
$pH$ value has to do with hydrogen ions. Water (H2O) molecule splits up to lose hydrogen and become hydroxide ions (OH−). Then this “lost" hydrogen ions combines with water molecules to form hydronium ions (H3O+). So, in general we can also say that the hydronium ions are referred to as hydrogen ions H+.
Hydrogen ions are being accepted by the base. So, when we mix base to the aqueous solutions then bases will absorb hydrogen ion concentration, or in the similar way there will be an excess of hydroxide ion concentration. Due to which, its $pH$ value becomes more than seven.
Acidity and alkalinity are measured by a negative logarithmic scale called pH.

Hence, the option (A) is the correct option.

Note: Pure water contains an equal number of hydrogen ions and hydroxide ions, so the solution is neither acidic or basic. And its $pH$value is equal to seven. In order to deal with these numbers more easily, scientists named Soren son derived a logarithmic scale, the pH scale.
$pH$$ = - \log \left[ {{H^ + }} \right]$