lisa is writing a formula to determine the number of elements in a list. she wants to ensure that a value is returned, even if the value her function is evaluating turns out to be a null string . which one of the following can she so to accomplish this ?（）

• A、use a defaule formula of 1 
• B、use @elements and add 1 to the total 
• C、use the @count function instead of @elements 
• D、use @texttotime to ensure that all strings arte converted to date-time values