The correct answer is B. Calendar.
Step-by-step explanation
The Mayan calendar is the calendar developed by the ancient Mesoamerican Maya society that inhabited the territory of present-day Mexico, this calendar consisted of different periods of time, for example, the sacred calendar was equivalent to 260 days; the solar cycle was equivalent to 365 days; the calendrical wheel was equivalent to 52 years; the long account was equal to 5200 years; the lunar cycle consisted of 18 lunar months; the Venus cycle was made up of 584 days; and the count of the lords of the night was 9 days. So, the correct answer is B. Calendar because the "long count" was a unit used by Mayan people as part of their calendar or to measure time.