Which two are true?

The CONCAT function and FLOOR function in Oracle SQL have specific behaviors:

A. CONCAT function joins two or more character strings into one string, making this statement true.

B. FLOOR function returns the largest integer that is less than or equal to the specified number, making this statement true.

C. While CONCAT can join two strings together, this statement is incomplete as it can join more than two.

D. INSTR can find the offset of a substring within a string, not just a single character.

E. INSTR starts searching the string from position 1 in Oracle SQL, not position 0.

F. FLOOR does return the largest integer less than or equal to the specified number, but it can be any integer, not just positive ones.

References:

Oracle Database SQL Language Reference, 12c Release 1 (12.1): "Single-Row Functions"