6.4.14. Watch the Unit 6 Part 4 lecture video and answer the following question: Why is it difficult to rate the strength of a tornado that is passing through a field of grass? Question 14 options: a. Because it is difficult to measure the wind speeds of a tornado with fixed doppler radar. b. Because the size of a tornado does not always indicate strength c. Because the tornado will not be causing much damage d. All the above