选择题
2018 AMC 8 Problem 19: Sign Pyramid
In a sign pyramid a cell gets “+” if the two cells below it have the same sign, and it gets “−” if the two cells below it have different signs. How many possible ways are there to fill the four cells in the bottom row to produce a “+” at the top?
2018 AMC 8 第 19 题：符号金字塔
在符号金字塔中，如果一个单元格下面的两个单元格具有相同的符号，则该单元格得到“ ”；如果它下面的两个单元格具有不同的符号，则该单元格得到“−”。有多少种可能的方法来填充底行的四个单元格以在顶部产生“ ”
A.
2
B.
4
C.
8
D.
12
E.
16