All options are incorrect
In this question we have a typo it should be str = 'Salesforce';
now the answer should be
either str.substr(0.4)
or str.substring(0,4)
here indexing will be like this
/**
* s = 0
* a = 1
* l = 2
* e = 3
* s = 4
* f = 5
* o = 6
* r = 7
* c = 8
* e = 9
*/
substr is a deprecated method of JS, but both methods work and both methods when take the 2nd parameters then they ignores the last index number and run throw the last index number - 1