The first option, collapsed in on itself.
The star's core mass becomes so dense that the resulting gravity implodes the star.
Interesting enough, the third option is kindof true too...some large and tenacious black holes that absorb other stars will form incredibly bright accretion disks around their perimeter before filling absorbing the star.
Answer is: reaction is second order with respect to a.
This second order reaction<span> is proportional to the square of the concentration of reactant a.
</span>rate of reaction = k[a]².
k is second order rate constant and have unit M⁻¹·s⁻¹.
Integrated rate law for this reaction: <span><span>1/[a]</span>=<span>1/<span>[a]</span></span></span>₀ <span>+ kt.
t is time in seconds..</span>
See which one is the bigger equitation to classify the smallest in order