Different combinations of values are missing and we need to write the same in mail what all are missing?

We are missing 3 values as A,B,C in our process and we can have different combinations of them being missing. So we want to write in mail what all we are missing.
for e.g. sometimes only A can miss, sometimes A,B can miss. Sometimes even A,B,C can even miss.
So we want to write like
“A is missing in process”
“A and B is missing in process” like that

If anybody can help here.

I’d use 3 IF activities, with yourstringvariable.ToString.Contains(“A").
If false build your statement.

Some more Details are needed. As you gave not enough details to datatypes and samples

Maybe evaluation against a required values list can help

When it is about the outputting: