In SQL the statement select*from R, S is equivalent to:(a) Select * from R natural join S(b) Select * from R cross join S(c) Select * from R union join S(d) Select * from R inner join S

(b) Select * from R cross join S

Explanation: The SQL query command, Select * from R, S selects each rows from table R and merges combines it with each row of table S such that the number of columns increases. The merging could be said to be horizontal in nature since it results in an increased number of data columns. The Cross join method produces the same exact result with the output all columns in both tables (R and S). The inner join combines rows in tables as well but requires that both tables have a matching column values. The union join merges data the data in both tables vertically and will not produce the same output as the SELECT * FROM R, S statement.

given the options, i would say your best bet is c. the modem supports up to 56 kbps, which is too low for video streaming. dial up modems use actual phone lines, which only can go up to 56 kbps as that's more than sufficient for traditional phone calls. this is also the reason why when a dial-up modem connects, you hear all those sounds. it's literally using the phone line to establish a connection.

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