A. implicit transient schemes
B. explicit transient schemes
C. quadratic schemes
D. high-resolution schemes
The question was asked in an internship interview.
The question is from Discretization Aspects topic in section Basic Aspects of Discretization, Grid Generation with Appropriate Transformation of Computational Fluid Dynamics
The explanation is: Courant number is used in explicit time integration methods involving numerical methods. It relates grid size and time steps of the explicit transient schemes. It cannot be applied for implicit transient schemes.