The correct answer is C) The Olmecs shared tool-making techniques with a contemporary culture.
The hypothesis that supports that the Olmec were not a "mother culture" but rather a "sister culture" is “The Olmecs shared tool-making techniques with a contemporary culture.”
When one civilization is a sister culture to others, is because it shares something in common. Otherwise, the appropriate word should be “influenced”, “inherit”, or “passed”. The Olmec shared many things with other cultures like sharing tool-making techniques with other Mesoamerican cultures. That is why some scientist and anthropologists have the hypothesis that the Olmec were not a "mother culture" but rather a "sister culture".