E: An execution plan is theresult of the query optimizer's attempt to calculate the most efficient way to implement the request represented by the T-SQL query you submitted. To generate the first execution plan, you can enable the Include Actual Execution Plan option.
B: SET STATISTICS TIME displays the number of milliseconds required to parse, compile, and execute each statement.
C: STATISTICS IO causes SQL Server to display information regarding the amount of disk activity generated by Transact-SQL statements. This is useful information for optimizing queries.
The information include Scan count:
Number of seeks/scans started after reaching the leaf level in any direction to retrieve all the values to construct the final dataset for the output.
Scan count is 0 if the index used is a unique index or clustered index on a primary key and you are seeking for only one value. For example WHERE Primary_Key_Column = <value>.
Scant count is 1 when you are searching for one value using a non-unique clustered index which is defined on anon-primary key column. This is done to check for duplicate values for the keyvalue that you are searching for. For example WHERE Clustered_Index_Key_Column = <value>.
Scan count is N when N is the number of different seek/scan started towards the leftor right side at the leaf level after locating a key value using the index key.