which of the following demonstrates how the 20 is calculated using the
combination pattern?

D

Step-by-step explanation:

The diagram shows Pascal's triangle. Pascal's triangle is a triangular array of the binomial coefficients.

The entry in the row (start counting rows from 0) and column (start counting columns from 0) of Pascal's triangle is denoted by

Coefficient 20 stands in 6th row, then n = 6 and in 3rd column, so k = 3.

Hence,