An amplitude modulates signal is plotted below
 

Which one of the following best describe the above signal?
 

Analysis of graph shows
(1)  Amplitude varies between
$8-10Vor9\pm 1$
(2)  two time period are
$100\mu s$ (modulating wave) &  $8\mu s$  (Carrier wave)
Thus modulated signal is  $[9\pm 1\sin \left(\frac{2\pi t}{T_1}\right)]\sin \left(\frac{2\pi t}{T_2}\right)$

$=[9\pm 1\sin (2\pi \times {10}^{4}t)]\sin (2.5\pi \times {10}^{5}t)$