SQL clustered index

I am using SQL Server 2008 R2. I have a table with columns Date, Time, ID(PK) , col1 , col2 , col3. Some of my queries uses date in where condition,while other uses date and time. The id column is rarely used in the query.

To improve the query performance on which column i need to create the clusterdindex?

Date column only ? Or date and time column ? Or date,time and id column ?