Which statement best describes the Moon cycle as given?

• A. The cycle lasts 29.5 days and includes waxing before waning.
• B. The cycle lasts 29.5 days but only waning occurs.
• C. The cycle lasts 12 hours.
• D. The cycle lasts 400 days.

Answer: (A)

Think about how the Moon’s appearance changes as it orbits Earth. The Sun lights only half of the Moon, and the portion we can see grows larger after a new Moon (waxing) until it reaches a full Moon, then shrinks (waning) back to a new Moon. It takes about 29.5 days to go from one new Moon to the next, a period called the synodic month that reflects the Sun–Earth–Moon geometry. So the statement that the Moon’s cycle lasts roughly 29.5 days and includes waxing before waning best describes what we observe. The other options misstate the length or skip the waxing phase, which is essential to how the cycle unfolds.