The correct answer is option A.) "joints; cooling and contracting during formation".
Explanation:
In Geology, a joint is a break or fracture that is naturally formed within a rock. Joints are formed as a result of cooling and contracting during its formation, or by the addition of layers of minerals during its formation.The rocks will break along their joints when they are hit with hammers because joints are their weak spots.
"At this time cow moose are malnourished and not yet recovered from the past winter's ticks. It seems too early, but an early start is essential so that calves are prepared to survive winter."