Form D80D - two questions I'm unsure about

1. My answer to question 4 is 05/01/15
Should my answer to question 5 be 05/01/15 - as in, we decided the same day she moved out that it was over
OR
should it be 05/01/17 - as in, we waited two years before I petitioned
OR
something else?

2. Confused on the whole 'A' and 'C' thing on the form.

Is it that A goes next to the signature on the copy of the Acknowledgement of Service and I only tick the box referring to A;

OR
is it that A goes at the top of the first page of the acknowledgement, C goes next to the signature, and I tick both boxes?
And if the latter, should I scrub out the A that I currently have written next to the signature as I originally put both A and C next to the same signature thinking that was what it was asking!?

Thanks so much. I consider myself a logical person but these forms ....aargh!