Step 1: Spot the contrast in the options.
Options 1 and 2 aim at sameness, either by absorbing groups or by one single idea. Option 4 is only about being readable. Option 3 alone is about unity along with difference.
Step 2: Use what we know about India.
The country has many languages, faiths and tribes. The Constitution lists many languages in a schedule, guards the rights of minorities and promises freedom of religion. These show that difference is accepted and protected.
Step 3: Link this to the options.
Because difference is accepted and written into law, the aim of unity through recognition matches option 3.
Step 4: Reject the rest.
An assimilationist or single idea nation-State would conflict with the rights to culture and religion. A mandate that everyone can read is a side goal, not the primary vision.
Step 5: Cross-check the result.
Double check with a simple example. India has many official languages, many faiths and protected minority rights, and yet it stays one nation. That is unity kept together by formal recognition of differences, which is the wording of option 3. A single code or a single idea would not allow this many recognised differences.
Final Answer:
Unity with recognised differences is the vision, option 3.
\[ \boxed{\text{Option 3}} \]