Which choice for the underlined material marked  best maintains the sentence pattern already established in this paragraph from the attached passage?
Measuring the dimensions of your science class is not a difficult task. All that is required is to obtain a tape measure and stretch it across the length and width of the floor. Finding the perimeter of your school’s athletic field, though offering a bit more of a challenge, is nonetheless within the realm of possibility.  A different method must be used, however, to find the distances between stars and galaxies.