Answer:
B and C
Explanation:
When the Amish came to their new home, they were founding a new colony. This is considered a founding effect.
Now, there is another thing to keep in mind, and that is that the Amish are very strict about their custom, for example, the idea of family and identity. This led them to form couples, only among the members who belonged to the community.
As generations go by, genealogical relationships between individuals in the population become closer. This causes some genes, by mere probability, to become fixed (i.e. they are the only ones left in the population). As a consequence of this, the frequency of rare genes increases (polydactyly). This evolutionary process is known as gene drift.
