Question: Which idiom can be used to concatenate the strings `a`, `b`, `c`?

1. `String::from(a,b,c)`
2. `format!("{}{}{}", a, b, c)`
3. `concat(a,b,c)`
4. `a + b + c`

Answer: The correct answer of the above question is Option B:`format!("{}{}{}", a, b, c)`