Teacher: In this task, you will be presented with a context passage, a question about that paragraph, and a possible answer to that question. The task is to check the validity of the answer. Answer with "Yes" or "No".
Teacher: Now, understand the problem? If you are still confused, see the following example:
Timothy likes to play sports. He spends his time after school playing basketball and baseball. Sometimes Timothy pretends he is a famous baseball pitcher for his favorite team with his friends. He plays with his friends Mandy and Andrew. Timothy also plays pretend when he is alone. He has an imaginary friend named Sean. Sean is an elephant who watches television with Timothy. Mandy likes playing baseball but she also likes to paint. Mandy's favorite class at school is art. She likes making pictures of flowers. Her teacher says she is a good artist. She painted a picture of a tree for her teacher. There were red and yellow leaves on it. It had apples on it. When Andrew goes home after baseball, he likes to eat a snack. He eats carrots and bananas. If he is a good boy his mom, Mrs. Smith, sometimes gives him milk and cookies. Afterwards, Andrew finishes his homework. <sep>Who does Timothy play with?<sep>Basketball and baseball
Solution: No
Reason: Based on the passage Timothy plays with his friends Mandy and Andrew. So, the given answer is incorrect and the output should be "No".

Now, solve this instance: The inhabited history of the Las Vegas Valley stretches to 23,000 b.c. , when much of the area was covered by a prehistoric lake. During this period, the indigenous people lived in caves, hunting the mammals that gathered at the shoreline. The landscape of the valley changed dramatically over the next 200 centuries. The glaciers feeding the lake melted away and the lake evaporated. Fossils tell an obscure story of man's slow and sporadic development. Around 3000 b.c. , native Archaic Indians began to develop a lasting hunting and gathering culture. By this time, the valley was in much the same geographic state as it exists in today, with one exception — the presence of artesian springs that bubbled to the surface in several areas. These springs fed a network of streams draining through the Las Vegas Wash to the Colorado River. The areas surrounding the springs were desert oases: sprawling collections of grasses, trees, and wildlife. Many springs lay in areas that would eventually become the center of the modern Las Vegas metropolis. For about 4000 years, the Archaics thrived in a culture that included many signs of early civilization. Signs of even more advancement appeared halfway through the first millennium a.d. , when the Anasazi Indians inhabited the valley. Far more progressive than the Archaics, the Anasazi utilized such formal agricultural techniques as irrigation to assist their harvest. This permitted the Anasazi to achieve a benchmark of advanced society — the ability to live in permanent shelters year-round without need to follow wildlife. Mysteriously, the Anasazi vanished from the valley around a.d. <sep>When did the artesian springs first appear?<sep>23,000 B.C
Student:
No