Question

Rainwater contains hydrogen of a heavy form called deuterium. The deuterium content of wood reflects the deuterium content of rainwater available to trees during their growth. Wood from trees that grew between 16,000 and 24,000 years ago in North America contains significantly more deuterium than wood from trees growing today. But water trapped in several North American caves that formed during that same early period contains significantly less deuterium than rainwater in North America today.Which of the following, if true, most helps to reconcile the two findings?(A) There is little deuterium in the North American caves than the deuterium in the water trapped there.(B) Exposure to water after a tree has died does not change the deuterium content of the wood.(C) Industrialization in North America over the past 100 years has altered the deuterium content of rain.(D) Trees draw on shallow groundwater from rain that falls during their growth, whereas water trapped in caves may have fallen as rainwater thousands of years before the caves formed.(E) Wood with high deuterium content is no more likely to remain preserved for long periods than is wood with a low deuterium content.

Answer 1

(D) Trees draw on shallow groundwater from rain that falls during their growth, whereas water trapped in caves may have fallen as rainwater thousands of years before the caves formed

Step-by-step explanation:

The above explanation, implies that water trapped in caves is not from the same period - 16,000 to 24,000 years ago. So, we cannot make appropriate comparisons about deuterium content.However, trees draw groundwater from rain, the heavy hydrogen components in the trees reflect the heavy hydrogen components of the rainwater. The heavy hydrogen component in the water is higher than the heavy hydrogen content in the trees now, the rainwater before 16000-24000 is higher than the current heavy rain.Obviously,option D discusses the difference between the two analog objects.