Choose A option is for a fixed rate which you don't have to worry about the rate movement and your monthly payment is fixed.
HELOC rate is determined by US prime rate + a bank spread. Today the prime is at 4.5% and HELOC is at around 5%. To get you signing up for the HELOC, your bank give you a first year rate of 3.24%, but goes up to 5% after one year. I am pretty sure that your HELOC rate will not be 5% next year this time. It will be somewhere 5.5% or even 6%. The reason being is that Feds is going through the rate normalization period by raising the interest rate and selling QE bonds. All these activities will make the interest rate go up and so does your HELOC rate. Good luck.
