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A body cools in a surrounding of constant temperature \( 30^{\circ} \mathrm{C} \). Its heat capacity is \( 2 \mathrm{~J} /{ }^{\circ} \mathrm{C} \). Initial temperature of the body is \( 40^{\circ} \mathrm{C} \). Assume Newton's law of cooling is valid. The body cools to \( 38^{\circ} \mathrm{C} \) in 10 minutes.

When the body temperature has reached \( 38{ }^{\circ} \mathrm{C} \), it is heated again so that it reaches to \( 40^{\circ} \mathrm{C} \) in 10 minutes . The total heat required from a heater by the body is:
(A) 3.6J
(B) \( 7 \mathrm{~J} \)
(C) \( 8 \mathrm{~J} \)
(D) \( 4 \mathrm{~J} \)
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