Rheumatoid arthritis is caused by: a. a bacteria b. a virus c. a reaction to an immunization d. an autoimmune reaction

In which situations is the principle of cross-cutting relationship useful in determining relative age?

What is true of sea slugs in these orders

How do plants obtain more sunlight a.) they lean towards the light b.)they grow straight up c.) they only live in sunny areas, like the tropics d.) they stay low to the ground