The author of the passage considers "current speeds" in order to A. identify a factor that undermines the significance of nest stone size for female river blennies B. indicate one possible advantage of river blenny nests that do not face southeast C. eliminate a possible explanation for a nest orientation tendency among female river blennies D. indicate why female river blennies are sensitive to both size and orientation of possible nests E. suggest a reason why many female blennies prefer southeast-facing nests