Each brand is trying to find a way to get a leg up on the competition in a tight market space. The above picture is what I found on my last grocery run. What caught my eye was the asterisk next to the non-GMO popcorn claim. My guess was the ingredients list would include soybean, canola, or corn oil.
The temperature for broiling in an oven is 260 degrees Celsius or  500 degrees Fahrenheit. Medium heat is about 177 degrees Celsius or  350 degrees Fahrenheit.
Like steaks, the longer a London broil cooks, the tougher the meat will be unless you are using the braising method of cooking. Roast a London broil roast in 350 degree oven for 30 to 35 minutes per pound for a rare roast. Add an additional 5 to 10 minutes per pound for a roast that is more well done.