3. (World database) All questions below are related to the following query Select co.name as "Name", sum (ct.population) "Major City Population" From Country co Join City ct on (co.code ct.countrycode ) Where co.continent 'Europe' Group by co.name; a. Is column alias used? How? b. Is table alias used? How? c. Is join used? What are the tables? d. Is there a selection operation involved? e. Is there a projection operation involved? f. Is any aggregation function used? Which one? g. Is grouping used? How? h. What the output looks like (number of columns, headers, a sample row, etc.)? 4. (World database) A relational algebra expression is nuitr me i Cownry comtinen Northmerica (City Country)) where F is the expression Country.code statement for the algebra expression - City countrycode. Write a SQL select