What is Oracle SQL Developer?

A.
An AWS developer who is an expert in Amazon RDS using both the Oracle and SQL Server DB engines

B.
A graphical Java tool distributed without cost by Oracle

C.
It is a variant of the SQL Server Management Studio designed by Microsoft to support Oracle DBMS
functionalities

D.
A different DBMS released by Microsoft free of cost

Explanation:
http://www.oracle.com/technetwork/developer-tools/sql-developer/what-is-sqldev-093866.html