Refer to the diagram of an index table. salesperson tablerecord salesperson number salesperson name city hire date commission rate 1 119 taylor, a new york 1/21/01 20% 2 137 baker, b detroit 2/3/11 10% 3 186 adams, a dallas 8/23/96 5% 4 204 dickens, s dallas 8/4/12 5% 5 255 lincoln, j atlanta 6/7/13 5% 6 361 carlyle, l detroit 11/11/10 7% 7 420 green, c tucson 9/25/12 11% 8 452 french, f new york 10/23/09 8%the database administrator has been tasked with implementing an index to speed up the retrieval of data based on the city values. the database is using the innodb engine. what is the correct syntax to create an index to be built on the city field based on the database information? (a) alter table `salesperson` add index 'city_index' (`city`) (b) create unique index city_index on salesperson (city); (c) create index city_index using hash on salesperson (city); (d) create index city_index on salesperson (city) using hash; (e) alter table `salesperson` add unique index 'city_index' (`city`)