Correct Answer: Orderly

Solution : The correct choice is the second option.

Tidy refers to being neat, well-organised, and in good order.
Orderly also means well-organised, systematic, and neat.

The meanings of the other options are:

• Muddy means covered in or containing mud, which is the opposite of tidy.
• Petty refers to something small or trivial.
• Nominal refers to something by name only, but not in reality.

Therefore, orderly is the most suitable synonym in this context.