Answer:
int i = 0; while (i < 4) { readData(); i = i + 1; }
Step-by-step explanation:
the above method is proper way to call the method readData four times because it will start from zero and will call readData until i=3, if i=4 it will stop calling readData.
double k = 0.0; while (k != 4) { readData(); k = k + 1; }
This is not the proper way to call readData four times because it will call readData only if k!=4 otherwise condition k!=4 will not be true and readData will not be called.
int i = 0; while (i <= 4) { readData(); i = i + 1; }
This is not the proper way to call readData four times because condition i<=4 will call readData five times starting from zero to 4.
int i = 0; while (i < 4) { readData(); }
This is not the proper way to call readData four times because it will call readData only one time i.e. value of is not incremented.