Step 1: Understand the question.
NEP 2020 set up a new school ladder. We must find the stage for students aged 11 to 14 years.
Step 2: Recall the new structure.
NEP 2020 replaced the old 10+2 pattern with a 5+3+3+4 pattern. This pattern has four named stages based on the age of the child.
Step 3: List the stages with their ages.
The Foundational stage covers ages 3 to 8. The Preparatory stage covers ages 8 to 11. The Middle stage covers ages 11 to 14. The Secondary stage covers ages 14 to 18.
Step 4: Match the given age.
The question asks about 11 to 14 years. From the list above, this band falls in the Middle stage.
Step 5: Rule out the others.
Foundational and Preparatory end before 11, and Secondary begins after 14. So they do not match the 11 to 14 band.
Step 6: Match with the options.
The third option, Middle stage, is correct.
\[ \boxed{\text{Middle stage}} \]