Please help ASAP! Will give brainliest! :)

When describing down syndrome, it's important to note that a. it can be classified as a single-gene disorder b. it is caused when red blood cells cannot properly form hemoglobin c. it causes infected males to have low testosterone levels d. it is usually caused by three copies of chromosome 21 select the best answer from the choices provided. a b

What are similarities and differences between refraction, reflection, diffraction and absorption?

Diamond will scratch quartz. true or false