GATE | GATE-CS-2003 | Question 30

Consider the following SQL query

select distinct al, a2,........., an
from r1, r2,........, rm
where P 

For an arbitrary predicate P, this query is equivalent to which of the following relational algebra expressions ? A: [Tex]\\prod_{a_{1},a_{2},...a_{n}}\\sigma_{\\rho} (r_{1}\\times r_{2}\\times r_{3}....\\times r_{m})[/Tex] B: [Tex]\\prod_{a_{1},a_{2},...a_{n}}\\sigma_{\\rho} (r_{1}\\bowtie r_{2}\\bowtie r_{3}....\\bowtie r_{m})[/Tex] C: [Tex]\\prod_{a_{1},a_{2},...a_{n}}\\sigma_{\\rho} (r_{1}\\cup r_{2}\\cup r_{3}....\\cup r_{m})[/Tex] D: [Tex]\\prod_{a_{1},a_{2},...a_{n}}\\sigma_{\\rho} (r_{1}\\cap r_{2}\\cap r_{3}....\\cap r_{m})[/Tex]