A. If it does not exist, an error is returned
B. If it does not exist, it is created
C. If it exists, then data is written at the end
D. If it exists, error is returned

Solution

B. If it does not exist, it is created

Explanation

In C, fopen() is used to open a file in different modes. To open a file in write mode, “w” is specified. When mode “w” is specified, it creates an empty file for output operations. If a file with the same name already exists, its contents are discarded and the file is treated as a new empty file.