In an experiment investigating the nature of matter, electrons with uniform momentum \(p\) are emitted toward a barrier containing two narrow slits separated by a distance \(d\). The emission rate is made extremely low so that, on average, only a single electron passes through the apparatus at any given moment before striking a sensitive detector screen. Which of the following pairs correctly identifies the appearance of an individual electron's arrival at the detector screen and the overall pattern formed after a large number of electrons have been detected?