Which of the following function headers is correct?

Question

Options

• Adef func(a=1, b=1, c=2):
• Bdef func(a=1, b=1, c=2, d):
• Cdef func(a=1, b):
• Ddef func(a=1, b, c=2):

• A
  81% (21)
• B
  12% (3)
• C
  4% (1)
• D
  4% (1)

Explanation

Option A is correct because all parameters with default values (a=1, b=1, c=2) appear together, which is valid Python - default arguments can all follow each other in any order. Options B, C, and D all violate Python's rule that non-default parameters cannot follow default parameters: in each case, a parameter without a default (d or b) appears after one with a default, which causes a SyntaxError. Python enforces this because if defaults could be followed by non-defaults, the interpreter couldn't determine which arguments the caller intended to pass positionally.

Memory tip: Think of it as a one-way door - once you open a default value, every parameter after it must also have a default. Any "bare" parameter (no =) must come before the first defaulted one.

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