Task: Question Generation
Input (English): Background Paragraph: Matter, dark matter, and dark energy are distributed homogeneously throughout the Universe over length scales longer than 300 million light-years or so. However, over shorter length-scales, matter tends to clump hierarchically; many atoms are condensed into stars, most stars into galaxies, most galaxies into clusters, superclusters and, finally, large-scale galactic filaments. The observable Universe contains approximately 300 sextillion (3×1023) stars and more than 100 billion (1011) galaxies. Typical galaxies range from dwarfs with as few as ten million (107) stars up to giants with one trillion (1012) stars. Between the larger structures are voids, which are typically 10–150 Mpc (33 million–490 million ly) in diameter. The Milky Way is in the Local Group of galaxies, which in turn is in the Laniakea Supercluster. This supercluster spans over 500 million light-years, while the Local Group spans over 10 million light-years. The Universe also has vast regions of relative emptiness; the largest known void measures 1.8 billion ly (550 Mpc) across. 
Story: Rob is an amateur astronomer. He was looking at the sky with his telescope. First he took a longer length observation. He noted his observation as case A. Then he took a shorter length observation. He noted that observation as case B. He found that it's beneficial to take both observations to get a fuller view of the observable universe.
Output (English): Which observation would not detect stars and galaxies well, case A or case B?