What is the expected output for the given code.
import pandas as pd
df = pd.DataFrame({"A":[12, 4, 5, 44, 1],
"B":[5, 2, 54, 3, 2],
"C":[20, 16, 7, 3, 8],
"D":[14, 3, 17, 2, 6]})
df.max(axis = 0)
1
A 44
B 54
C 20
D 17
B 54
C 20
D 17
2
A 1
B 2
C 3
D 2
B 2
C 3
D 2
3
A 12
B 5
C 20
D 14
B 5
C 20
D 14
4
A NAN
B 2
C NAN
D NAN
B 2
C NAN
D NAN