I suspect you are wondering if it's 2,100ft or 3,000 ft.... But class E only goes to 2,500ft.
You have asked a trick question, as you didn't specify under or over the cloud so in fact, the answer would be as high as I am allowed in Class C airspace subject to the limitations of my aircraft and equipment as I could very well be VFR over the top at even 8,000+ or more for example.
You also didn't say OCTA or not so of you intended to fly through VFR OCTA with 3,100 overcast you might be out of luck.... Is that what you are thinking?