Suppose the alphabet $=\{a,b\},$ and suppose the grammar is $S|$ aS $|$ bS$.$ Which of the following is a correct description of the language specified?

Any string consisting of a$\text{'}$s and b$\text{'}$s$,$ including the empty string

All strings of the form $a^n{b}^m$ that is$,$ some $a^{\text{'}}$ s followed by some b$\text{'}$s

All strings with an equal number of $a^{\text{'}}$ s and b$\text{'}$s

Any combination of a$\text{'}$s and b$\text{'}$s that starts with an a