MATLAB HELP

I dont understand how to do this without using MATLAB. Could someone give some steps to solving this problem? I am also unsure how s(i-1:i) = 'AB' when I checked with MATLAB.

13. After the following script is executed, what is the value of max(c)? S-'ABAABAABAB'; for i-2:length(s) switch s(-1:i) case AA A. 2 B. 3 C. 4 D. 5 E. 6 case 'AB' otherwise end end