Why am I getting undefined in my javascript code [closed]

I am trying to solve a question such that if someone scores a score between 0 and 5, he/she has a grade of F, if they have a score above 5 and below or equal to 10 they have E and so on. I have written my answers but I don't know I am getting undefined on the next.

Question Image:

My Answer:

function getGrade(score) {
    let grade;
    // Write your code here
    if (score >= 0 && score <=5) {
        console.log("F");
    }
    else if (score > 5 && score <=10) {
        console.log("E");
    }
    else if (score > 10 && score <=15) {
        console.log("D");
    }
    else if (score > 15 && score <=20) {
        console.log("C");
    }
    else if (score > 20 && score <=25) {
        console.log("B");
    }
    else if (score > 25 && score <=30) {
        console.log("A");
    }
    return grade;
}

getGrade(11)