Final answer:
The implication that the Mayan civilization existed for at least 900 years is true, based on the historical records indicating a cultural presence from around the first century A.D. to advancements in the tenth century.
Step-by-step explanation:
The first paragraph states the Mayan culture developed in Mexico around the first century A.D. and implies another cultural and scientific advancement occurred in the tenth century. If we consider the first century as a starting point and the tenth century as an indication of ongoing advancement, this suggests the Mayan civilization existed for at least 900 years, which aligns with the historical periods mentioned for the Mayan civilization's classical era (250 CE - 900 CE). Therefore, the statement in the first paragraph implies that the Mayan civilization existed for at least 900 years is true.