C

Young's modulus is a measure of the stiffness of a solid material and is defined as the ratio of tensile stress to tensile strain. The units of Young's modulus consist of pressure units, which can be expressed in several ways.

• Option A represents a unit of pressure (Tension).
• Option B also represents a unit of pressure (Pascals).
• Option D is Mega Pascal, which is another unit of pressure.
• Option C is Dine per centimeter squared, which is also a pressure unit, but is less commonly used in modern engineering.

However, out of the options, the Dine per centimeter squared can be seen as a less standard unit compared to the other options, which are more prevalent in scientific contexts. Therefore, Option C is not a standard unit of Young's modulus.
Therefore, C.