1. (a) >= and <= is true about the given condition
The option a is true because between operator always include the given number (minimum range) and it ranges till the maximum range of numbers and include the maximum number.
For example: number between 20 and 25 implies that, we need to obtain the following numbers: 20, 21, 22, 23, 24, 25. So it includes both 20 (minimum range) and 25 (maximum range).
2. Alias' is used for table and columns to make the names easier to understand
Alias is nothing but another name given to the table or column to make the user to better understand the result. The table and column can have its own technical name
Eg. col_empname but when it is displayed to the user it should be “employee name”, so that the end users understands easily.