I understand the concept of Schmitt Trigger where there is 2 transition threshold points so that input changing between the hysteresis would not create output transitions . The very first observation that I made in this design requirement is the overlap/ hysteresis is between +1 and -1, so shouldn't the threshold be +1 and -1. So can threshold be +2 and -2 as in the options ? Are there more points to consider while deciding threshold ? Can I say as a thumbrule that the overlapping segment of inputs should always be included in the hysterisis that is here between +1 and -1, anything more is always good but that should always be less than the Maximum and minimum that is here +7 and -7?