In the summer of 1947, Kenneth Arnold was flying his airplane over the mountains near Seattle, WA when he supposedly saw a group of unknown ships flying. He tried measuring their size by holding up an object of known size and comparing the flying saucers size to the size of a nearby commercial airplane. Why was his method of measurement incorrect? Group of answer choices a. He did not know the distance to each object and therefore cannot calculate the correct angular size of the object b. The object he used did not have any ruler markings on it c. He could not see both objects at the same time d. Measurements can only be made if all the objects are not moving