13. It can reasonably be inferred from the passage that
before Harrison’s efforts, other individuals trying to
solve the longitude problem had failed to:

  • A. consider clocks as the potential instrument of calculation.

  • B. agree on why longitude decreases in value at
    increasing distances from Earth’s equator.

  • C. improve upon the features of clocks that made
    them unreliable at sea.

  • D. understand the ways that charts and compasses
    could be used in connection with timepieces to
    calculate longitude.