Energy over time is found by multiplying power by how long it runs. Power in watts times time in hours gives energy in watt-hours. To express that energy in kilowatt-hours, you divide by 1000 because 1 kilowatt equals 1000 watts. So the clear way to write the conversion is kWh = (Watts × Hours) ÷ 1000. This shows exactly how to scale watt-hours into kilowatt-hours. For example, a 100 W device running for 2 hours uses 100 × 2 = 200 Wh, which is 0.2 kWh since 200 ÷ 1000 = 0.2.

Reflecting telescopes use mirrors to collect and focus light, and mirrors can be built very large while staying relatively lightweight. This means you can create a telescope with a large aperture, which gathers more light and tightens the diffraction limit, giving brighter and sharper (clearer) images. Because mirrors reflect all colors the same way, there’s no chromatic aberration to blur colored edges around objects, which helps maintain image clarity as you build bigger instruments. That combination—large aperture possible with mirrors, plus minimal color distortion—is why an advantage of reflecting telescopes is that they can be made big and yield clearer images. Light loss and maintenance considerations exist (mirror coatings wear, alignment can be needed, and not every design is cheaper in every case), so those factors don’t trump the main benefit of scalable, high-quality image performance.

Understanding who proposed the DNA double helix is about recognizing the scientists who put together the model of DNA’s structure. James Watson and Francis Crick proposed the double helix in 1953, building a picture of two long strands wound around each other with a sugar-phosphate backbone on the exterior and bases pairing inside. This arrangement, with A pairing with T and G pairing with C, explains how genetic information can be accurately copied because each strand can serve as a template for making the other. Their model drew on Chargaff’s base-pairing rules and X-ray diffraction data collected by Rosalind Franklin (and Maurice Wilkins), which pointed to a helical shape. Darwin and Mendel made foundational contributions to biology, but not to the specific structure of DNA.

The sequence being tested reflects the order of taxonomic ranks from broadest to most specific as presented: Kingdom, Phylum, Class, Order, Family, Genus, Species. This aligns with the standard hierarchy where each step narrows classification, with Species being the most specific category. In this material, Domain is not included in the basic ranks, so starting with Kingdom is considered the broadest level shown. That makes the sequence that starts with Kingdom and proceeds in the correct order the best choice. The other options fail because they either swap the relative positions of ranks (placing Class before Phylum, or placing Genus after Species) or they add Domain, which isn’t part of the presented list.