Step 1: Understand the question.
We must find which body conducts the National Achievement Survey, the NAS. This survey checks how well school students are learning across India.
Step 2: Know what each body does.
NCTE looks after teacher education. UGC handles higher education like colleges and universities. ASER is a private citizen-led report, not the government NAS.
Step 3: Focus on school learning surveys.
The NAS is a government survey for school classes. The body that prepares school textbooks, curriculum, and national surveys for schools is NCERT.
Step 4: Match the work to the body.
Since NAS measures learning levels in school subjects and classes, it fits the work of NCERT, which is the national council for school education research.
Step 5: Eliminate the rest.
NCTE, ASER, and UGC each do other jobs, so they cannot be the conductor of NAS.
Step 6: Match with the options.
The fourth option, NCERT, is correct.
\[ \boxed{\text{NCERT}} \]