Arrays - General Questions

For a 2-D array stored in column-major order, which elements are adjacent in memory?

For a 2D array A[10][20] stored in row-major order with base address 1000 and 4-byte elements, what is the address of A[2][5] (0-based)?

Prefix sums let you answer a range-sum query in:

For A[5][6] in row-major order with base address 2000 and 2-byte elements, the address of A[2][3] is:

What is the output of the following code?

a = [3, 8, 1, 9, 4]
best = a[0]
for x in a:
    if x > best:
        best = x
print(best)