How is search done in #include and #include "somelibrary.h" according to C standard?

• A. When former is used, current directory is searched and when latter is used, standard directory is searched
• B. When former is used, standard directory is searched and when latter is used, current directory is searched
• C. When former is used, search is done in implementation defined manner and when latter is used, current directory is searched
• D. For both, search for ‘somelibrary’ is done in implementation-defined places