The most accurate response regarding the influence of the Olmec civilization on other civilizations in the Americas is: use of pyramids adopted by other civilizations such as the Aztecs.
The Olmec civilization, often considered the "mother culture" of Mesoamerica, is known for its monumental architecture, including pyramids and large ceremonial complexes, which set a precedent that was followed by later civilizations such as the Aztecs and Maya. The other options provided, such as universality of the Olmec language or engineering advances relating specifically to the construction of Machu Picchu (which was built by the Inca, not the Aztecs), are not accurate representations of Olmec influence.