Consider the following grammar:

<a> ::= 0 <b> | 1 <c> | ε
<b> ::= 0 <a> | 1 <d>
<c> ::= 0 <d> | 1 <a>
<d> ::= 0 <c> | 1 <b>

Which one of the following strings CANNOT be derived from <a>?

101
  • 1100
  • 001010
  • 1111

Try to build a complete derivation with pencil and paper for each string.

Each derivation must start with the non-terminal <a>.