I just went through something similar with JohnQ. He felt 'Options' (as opposed to only 'Standards') can be used for Warrant 1 on a PE exam question. It was and still is my strong opinion that, unless specifically directed in the problem statement that "Options" can be used, I feel the only correct and proper way to answer these Warrant 1 questions is by using only the Standards (not Options). With that said, this problem does clearly state that "optional criteria" can be used. Thus, the solution's use of the 70% column.
Standard Condition A using 100% does not meet the VPH for the minor street. Standard Conditions A and B using 80% also does not meet the VPH for the minor street (Cond A) or the VPH for the major street (Cond B).
Now, because the problem statement indicates that the use of Options is valid, and the speed of the major street is > 40mph, check Option Condition A using 70%. The VPH for the major and minor for the same 8 hours is met.
To answer your question, yes, within the same condition (in this case Condition A), you need to use the same 8 hours for the major and minor streets. In this case all 12 hours of the Major street have a VPH over the minimum needed 420 VPH. Therefore, any eight hours that the minor street meets or exceeds 105 VPH, the Warrant will be satisfied.
Does that help?