What is Oracle SQL Developer?

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