Final answer:
The duration of daytime and nighttime varies throughout the year and depends on factors such as the time of year and the observer's latitude. The option that provides the closest approximation is 1/2 hr. after sunrise and 1/2 hr. before sunset.
Step-by-step explanation:
The duration of daytime and nighttime can vary depending on various factors such as the time of year and the observer's latitude. However, in general, the duration of daytime and nighttime is not fixed and varies throughout the year. The option that provides the closest approximation is 3) 1/2 hr. after sunrise and 1/2 hr. before sunset. During this time, the Sun is above the horizon, providing daylight, while at other times it is below the horizon, resulting in nighttime.