In the following passage, some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.
Starting late-2014, scientists of the National Aeronautics and Space Administration (NASA) working _______ satellite data tracking the rift found that the defect in the Larsen C was growing _________. By 2016 the crack became 70 miles long and 300 feet ________. By January 2017 it measured 109 miles in length and 1,500metres in breadth. On July 12, it broke. The broken shelf, now __________ official iceberg, was massive, indeed the ____________-ever such iceberg, weighing 1.1trillion tons and measuring 2,200 square miles.
Administration (NASA) working _______ satellite data tracking