Add properties in existing html string using c#.net

Hello.
I have one situation where I have html string in session like below :-

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<div id="DivQuestion"><div class="imgQuestion" id="divTextBx" style="text-align:right; position:relative; width: 666px;"><img src=""><div style="left:204px;position:absolute;width:300px;top:96px;margin-top:-23px;text-align:left;line-height: 23px;" id="draggable296-10"><span id="lbl296-10" style="text-align:left;width:30px; height:10px;font-size: 22px;font-weight:bold;color:#000000;">Select Prime numbers ?</span></div><div style="left:257px;position:absolute;width:0px;top:130px;margin-top:-23px;text-align:left;line-height: 23px;" id="draggable297-10"><div style="z-index:1000;position: absolute;"><div class="squaredTwo" style="float:left;margin-right:10px;"><input id="297_10" name="chkLov" value="" type="checkbox"><label for="squaredTwo"></label><span style="font-size: 22px;">20</span></div></div></div><div style="left:257px;position:absolute;width:0px;top:160px;margin-top:-23px;text-align:left;line-height: 23px;" id="draggable298-10"><div style="z-index:1000;position: absolute;"><div class="squaredTwo" style="float:left;margin-right:10px;"><input id="298_10" name="chkLov" value="" type="checkbox"><label for="squaredTwo"></label><span style="font-size: 22px;">17</span></div></div></div><div style="left:256px;position:absolute;width:0px;top:192px;margin-top:-23px;text-align:left;line-height: 23px;" id="draggable299-10"><div style="z-index:1000;position: absolute;"><div class="squaredTwo" style="float:left;margin-right:10px;"><input id="299_10" name="chkLov" value="" type="checkbox"><label for="squaredTwo"></label><span style="font-size: 22px;">19</span></div></div></div></div></div>
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In this, I have created check boxes run time and pass it to view for rendering.
Now, I want to add selected / checked propery in existing html string in c# depending of parameter / conditions.
Its like, I have given question to student with options of check box.
Once student submit the answer, I want to store answer given by Student. So, I want to add above properties while saving result into database.