Concept: Article 39A is a Directive Principle of State Policy. It directs the State to ensure equal justice and free legal aid.
Step 1: Understand the purpose of free legal aid.
Free legal aid ensures that justice is not denied to any person because of poverty, disability or other economic disadvantage.
\[
\text{Free legal aid} \Rightarrow \text{Access to justice for all}
\]
Step 2: Identify the constitutional provision.
Article 39A specifically provides for equal justice and free legal aid.
\[
\text{Article 39A} = \text{Equal justice and free legal aid}
\]
Step 3: Choose the correct answer.
Since Article 39A directly mentions this principle, the correct answer is Article 39A.