Statistics MultiColumn created Automatically With PrimaryKey

Hi Folks,

In my SQL server statistics are created with Multi column automatically.

All column is created with  Primary key column. 

I don't know why it's created.I read some experts blog they told SQL statistics wont create a multiple column automatically.

May i know the reason why it is create like that and may it will degrade the performance or it's good for SQL Server.

Here i Attached the table statistics detail

I Highlighted the columns are created automatically.

ActivityID --> Primary Key of the Table.

It will created automatically with other columns.

Please help me!!!

Thanks For the Advance,

BY

RamKarthik K N