|Which of the following is not true about an increasing greenhouse effect?||b) nighttime temperatures may increase, but daytime temperatures will not|
No, that is incorrect.
That statement is true. A warmer atmosphere will allow more humidity and water vapor (clouds) to form. Water vapor, especially white clouds, is powerful solar reflectors - they may even cool daytime temperatures slightly. Any warming, if it does occur, will likely occur as a decrease in the amount of nighttime temperature drop.
Similarly, it is the driest and coldest regions of the Earth that would notice the biggest change - places such as Siberia and Canada. Warmer winter nights in the Arctic Circle are a problem for no one or nothing.