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Que. A table 'student' with schema (roll, name, hostel, marks), and another table 'hobby' with schema (roll, hobbyname) contains records as shown below:

Table: Student

ROLL NAME HOSTEL MARKS
1798 Manoj Rathod 7 95
2154 Soumic Banerjee 5 68
2369 Gumma Reddy 7 86
2581 Pradeep Pendse 6 92
2643 Suhas Kulkarni 5 78
2711 Nitin Kadam 8 72
2872 Kiran Vora 5 92
2926 Manoj Kunkalikar 5 94
2959 Hemant Karkhanis 7 88
3125 Rajesh Doshi 5 82  

Table: hobby

ROLL HOBBYNAME
1798 chess
1798 music
2154 music
2369 swimming
2581 cricket
2643 chess
2643 hockey
2711 volleyball
2872 football
2926 cricket
2959 photography
3125 music
3125 chess
The following SQL query is executed on the above tables:

select hostel
from student natural join hobby
where marks > = 75 and roll between 2000 and 3000;
Relations S and H with the same schema as those of these two tables respectively contain the same information as tuples. A new relation S’ is obtained by the following relational algebra operation: S’ = ∏hostel ((σs.roll = H.roll (σmarks > 75 and roll > 2000 and roll < 3000 (S)) X (H)) The difference between the number of rows output by the SQL statement and the number of tuples in S’ is  
a. 6
b. 4
c. 2
d. 0
Answer:4
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