What does it mean to have parfocal objectives? a) The whole sample is in focus
b) Focusing on the sample is done automatically
C) The sample remains in focus when the stage is moved laterally
d) The sample remains in focus when the objectives are changed.

Which of the following is true about the introduction of a non-native species to an environment? (a) they usually adapt quickly so they can have a positive affect on the environment. (b) they can disrupt the environment and cause much damage and devastation to native species. (c) they usually become predators in a food chain and to keep prey populations under control. (d) because the native species are better-adapted to the environment, the non-native species always end up dying out.