Whales originated
Whales originated in the freshwater lakes and rivers of ancient Asia about sixty million years ago. Not until about ten million years later did species of whales develop specialized kidneys enabling them to drink salt water. Although fossil evidence shows that some early whale species that lacked such kidneys sometimes swam in the Earth’s saltwater oceans, these species must have had to return frequently to freshwater rivers to drink.
Which of the following is most strongly supported by the information given?
(A) Fossils of whale species dating from between sixty million and fifty million years ago will not be found on continents that were at the time separated from ancient Asia by wide expanses of ocean.
(B) Among whale fossils that date from later than about fifty million years ago, none are fossils of whale species that drank only fresh water.
(C) Fossils of whale species that drank fresh water will not be found in close proximity to fossils of whale species that drank salt water.
(D) The earliest whales that drank salt water differed from fresh-water-drinking whales only in their possession of specialized kidneys.
(E) Between sixty million and fifty million years ago, the freshwater lakes and rivers in which whales originated were gradually invaded by salt water.
Very confused reading the premise. how to eliminate options?
Hi Riya,
Data point 1 – Whales originated in the freshwater lakes and rivers of ancient Asia about sixty million years ago.
Data point 2 – Only ten million years later species of whales developed specialized kidneys enabling them to drink salt water.
Data point 3 – Even without such kidneys, sometimes whales swam in the Earth’s saltwater oceans, but these whales must have had to return frequently to freshwater rivers to drink water.
Based on the above data, we can conclude that whales that originated in the freshwater lakes and rivers of ancient Asia about sixty million years ago (data point 1) will have to stay in the freshwater or will have to keep returning to the freshwater because they lack specialized kidneys.
Option A summarizes the above inference. Fossils of whale species dating from between sixty million and fifty million years ago will not be found on continents that were at the time separated from ancient Asia by wide expanses of ocean. An ocean is a saltwater body and hence the whales could not have traveled across oceans to the other continents because they would have had to return to the freshwater body for fresh water.
We do not have adequate data to infer any of the other options. An inference answer needs to be 100 % true based on the data given to us.
Hope this helps!
