indeed, without immediate help, many people in America face a startling dilemma: hunger.
Commas are placed in a sentence in order to separate two clauses that have "but" or "and" in between. We prefer semicolons when we have to separate two independent clauses that don't have any conjunction, and we use a colon when we want to introduce an enumeration, or when we will introduce an explanation of the precedent clause. In this case, we are introducing an explanation because we are showing that the dilemma is hunger, so a colon is employed.