[2clients]

 Hello, I'm having trouble formatting the question, so I attached a screenshot.  I think it is choice 1, 3, or 5, and I think 3.  I've determined that it is a first order reaction because the concentrations are changing in the same proportion.  I've determined that the units must be molarity per seconds, though I'm not sure about the proportionality constant (whether it's # 3 or 5) and the units (whether it's #1 or 3).  #1 does not show [A], and I'm having trouble figuring whether [A] is redundant or necessary.

Thank you