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The relational algebra expression equivalent to the tuple calculus expression

$\{t\mid t ​ \in ​ r \land (t[A]=10 \land t[B]=20)\}$ is

1. $\sigma_{(A=10\:\lor\:B=20)}(r)$
2. $\sigma_{(A=10)}(r)\cup\sigma_{(B=20)}(r)$
3. $\sigma_{(A=10)}(r)\cap\sigma_{(B=20)}(r)$
4. $\sigma_{(A=10)}(r)-\sigma_{(B=20)}(r)$

Option C

t ia table have two attribute A,B

$({t∣t​∈​r∧(t[A]=10∧t[B]=20)}$ MEANS one of the tuple of table t value of A=10 and B=20

 t.A t.B 10 20 30 40

here r is table with attribute A,B

$σ(A=10)(r)∩σ(B=20)(r)$ means one of the tuple of table r value of A=10 and B=20