Ques not clear i choose 1 BUT IT SEEMS INCORRECT

#1

which of the following is not valid?
A)abc = 2234,2341,000
B)a b,c=123222,564,93
C)a,b,c = 1209,000,765
D)a _ b_c=1

please cleaify answer

#2

option B is the correct one here as
in a the abc is given the value of the numbers a tuple
in c each of the numbers are assigned a value
in d a single variable is assigned the value 1

only in b we have a space , and variables in python do not have spaces between them