GPA Calculator not Returning Corresponding Grades

Question

I'm trying to calculate a student's GPA in C programming language with the code below but it's not returning the correct corresponding grade based on each score, feels like it just picks a random letter.

#include <stdio.h>
#include <stdlib.h>
#include<math.h>

float gpa_ICT(int a){

    float point[a], unit[a], score[a];
    char C_code[12][6][a];
    char grade[a];

//Read Course code, score and unit
    for(int x = 0; x < a; x++){
        printf("Enter Course Code: ");
        scanf("%6s", &C_code[x]);
        printf("Enter course score: ");
        scanf("%f", &score[x]);
        printf("Enter course unit: ");
        scanf("%f", &unit[x]);

        //Assign values to Course point and Grade based on Score.
        if(score[x] >= 70){
            grade[x]= "A";
            point[x] = 5;
        }
        else if (score[x] >= 60 && score[x] <=69){
            grade[x]= "B";
            point[x] = 4;
        }
        else if (score[x] >= 50 && score[x] <=59){
            grade[x]= "C";
            point[x] = 3;
        }
        else if (score[x] >= 45 && score[x] <=49){
            grade[x]= "D";
            point[x] = 2;
        }
        else if (score[x] <=44){
            grade[x]= "F";
            point[x] = 0;
        }
        else{
           printf("ERROR!");
        }
    }


//Check score for each course
//Return the Course Code and grade based on score
    for(int i = 0; i < a; i++){
        printf("%s : %c\n",C_code[i] ,grade[i]);
    }

//Multiply each point by corresponding course unit and sum them up
    float sum = 0;
    float Total;
    for(int y = 0; y < a; y++){
        Total = point[y]*unit[y];
        sum = sum + Total;
    }

//Calculate the total Course unit
    float totalUnit = 0;
    for(int z = 0; z < a; z++){
        totalUnit = totalUnit + unit[z];
    }

    //Calculate the GPA
    float GPA = sum / totalUnit;

    return GPA;
}

int main()
{
    int course;
    printf("How many courses? ");
    scanf("%d", &course);


    float result = gpa_ICT(course);
    printf("Your GPA is %0.2f", result);
    return 0;
}

Here is the output How many courses? 3

Enter Course Code: MTS202

Enter course score: 75

Enter course unit: 3

Enter Course Code: ICT202

Enter course score: 58

Enter course unit: 2

Enter Course Code: MEE202

Enter course score: 65

Enter course unit: 2

MTS202 : D

ICT202 : H

MEE202 : F

Your GPA is 4.14

Process returned 0 (0x0) execution time : 32.212 s Press any key to continue.**