ANS:E - All the above.

1. Coefficient of compressibility is the decrease in void ratio per unit increase of pressure: This statement is generally correct. The coefficient of compressibility represents the change in void ratio per unit increase in effective stress or pressure. It quantifies the compressibility of soil under loading.
2. The percent settlement at any time is called the degree of consolidation: This statement is incorrect. The percent settlement at any time is typically referred to as the settlement or compression, while the degree of consolidation (Cv) is the ratio of actual settlement to the settlement that would occur if consolidation were instantaneous.
3. Time factor is a dimensionless quantity: This statement is correct. The time factor (T) used in the context of consolidation theory is indeed a dimensionless quantity. It is calculated using time and the coefficient of consolidation (Cv) to represent the rate of consolidation.
4. The initial curve on either side of the point of unloading and reloading is called the 'virgin curve': This statement is incorrect. The initial curve on either side of the point of unloading and reloading in a stress-strain or stress-pore pressure plot is typically referred to as the "loading-unloading curve" or "reloading curve."