Researchers have investigated bidirectional transport in phloem by applying different radioisotope tracers to two source leaves and monitoring a point between the two sources for the presence of the tracers. Which of the following observations would not support the pressure- flow hypothesis? Appearance of the two tracers in
A) a single sieve- tube member. B) sieve- tube members of different vascular bundles. C) adjacent sieve- tube members of the same vascular bundle.