Scientists are convinced that other stars have planets in orbit about them. Without visiting
these distant solar systems, how can they be sure?

answer; i believe that the correct answer is(d) nondisjunction during meiosis;

you must remain stopped until the stop signal is retracted and the red lights are turned off. approaching traffic in the opposite roadway of a divided highway shall not be required to stop, even if the school bus has the stop-arm extended and the alternately flashing warning signal lamps on.