Was this problem graded wrong or was I wrong???

I dont want to put any photos of my work or the "practice" question here so ill do my best to explain.

The question given was word for word "What is the strength of the magnetic field at the center of a circular coil of wire of diameter d = 20 cm, if the electric current in the wire is 7 amperes. Write your answer in microtesla." So I used the formula (μ₀I)/(2R) and got 44 microtesla, but I was told it was wrong and the answer is actually 14microtesla. The reasoning being I used the straight wire formula instead of the circular loop formula, that formula being (μ₀I)/(2πR). Using this does get you the supposed correct 14microtesla but doesnt make sense as the question literally states "circular coil" NOT 'straight wire"

Someone please help I am losing it...