Generally with a Crime Fiction Essay they will specify "at least". These at least values will be 2 in most cases (both for core and supp texts). In this case talk about 2.
If they ask for at least 1, talk about 2 anyway, chances are you've prepped 4 texts (2core 2supp) for 2 conventions (or more or less depending on your writing speed). Do what you're most comfortable with.
But most importantly: ATQ, ATBQ, ATFQ.
cheers