A, B, C and D are students. They are studying in four different cities, viz. P, Q, R and S (not necessarily in that order). They are studying in Science college, Arts college, Commerce college and Engineering college (not necessarily in that order), which are situated in four different States, viz. Gujarat, Rajasthan, Assam and Kerala (not necessarily in that order). Further, it is given that—
(i) D is studying in Assam
(ii) Arts college is located in city S which is in Rajasthan
(iii) A is studying in Commerce college
(iv) B is studying in city Q
(v) Science college is located in Kerala

Which one of the following statements is correct?

To determine the correct statement, let's systematically analyze the given information and construct a mapping of the students, their colleges, their cities, and the states where they study.

We have four students: A, B, C, and D.
Four cities: P, Q, R, and S.
Four types of colleges: Science, Arts, Commerce, and Engineering.
Four states: Gujarat, Rajasthan, Assam, and Kerala.

Let's analyze the clues step-by-step:
1. Clue (i) states that D is studying in Assam.
2. Clue (ii) states that the Arts college is located in city S, which is in Rajasthan. This means:
City S = Rajasthan = Arts college.
Since D is in Assam, D cannot be in city S or studying in the Arts college.
3. Clue (iii) states that A is studying in the Commerce college.
4. Clue (iv) states that B is studying in city Q.
5. Clue (v) states that the Science college is located in Kerala.
Since the Arts college is in Rajasthan (state) and the Science college is in Kerala (state), the remaining two colleges (Commerce and Engineering) must be located in the remaining two states (Gujarat and Assam).

Now, let's map the colleges to the states:
We know A is in the Commerce college.
Since D is in Assam, and the Science college is in Kerala, D cannot be in the Science college. Since the Arts college is in Rajasthan, D cannot be in the Arts college either. Since A is in the Commerce college, D cannot be in the Commerce college. Therefore, D must be in the Engineering college.
Since D is in Assam, and D is in the Engineering college, it directly follows that the Engineering college is located in Assam.

Let's verify the options:
- "Engineering college is located in Assam.": This matches our deduction.
- "City Q is situated in Assam.": Let's check B. B is in city Q. Since D is in Assam, if Q were in Assam, B would be in Assam, which conflicts with D being the one in Assam (each student is in a different city/state). So this is incorrect.
- "C is studying in Kerala.": Let's check who is in Kerala (Science college). D is in Engineering (Assam). A is in Commerce. The Arts college is in S (Rajasthan). That leaves B and C. Since B is in city Q, and Science is in Kerala, we can determine the exact distribution, but we already have a uniquely true statement.

Thus, the correct option is: "Engineering college is located in Assam."