$A$ student measuring the diameter of a pencil of circular cross-section with the help of a vernier scale records the following four readings: $5.50\, mm, 5.55\, mm, 5.45\, mm, 5.65\, mm$. The average of these four readings is $5.5375\, mm$ and the standard deviation of the data is $0.07395\, mm$. The average diameter of the pencil should therefore be recorded as:

• A
  $(5.5375 \pm 0.0739)\, mm$
• B
  $(5.538 \pm 0.074)\, mm$
• C
  $(5.54 \pm 0.07)\, mm$
• D
  $(5.5375 \pm 0.0740)\, mm$