If you flipped a penny 99 times and each time it came up heads, then the chance of the penny coming up heads again is . 50% 1% 100% 25%

The chance of coming up heads 99 times in a row is abysmally small: 50%^99 = 1.57 * 10^-30. This however has already happened, it does not influence the next penny flip. A penny has two sides, so the chance of it landing on one side is 1/2 = 0.5 = 50%. So the result of the next flip has a chance of 50% of coming up heads.