Teacher:You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.
Teacher: Now, understand the problem? Solve this instance: Question: Average age of students of an adult school is 42 years. 120 new students whose average age is 32 years joined the school. As a result the average age is decreased by 4 years. Find the number of students of the school after joining of the new students.

Option A: 1200

Option B: 120

Option C: 360

Option D: 200

Option E: None of these
Student:
Option D