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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

- $\sigma_{(A=10\:\lor\:B=20)}(r)$
- $\sigma_{(A=10)}(r)\cup\sigma_{(B=20)}(r)$
- $\sigma_{(A=10)}(r)\cap\sigma_{(B=20)}(r)$
- $\sigma_{(A=10)}(r)-\sigma_{(B=20)}(r)$