25 mina is testing different types of heat lamps to determine which type is most effective for growing strawberry bushes. she purchases two different types of lamps from a local store. mina applies brand a to one area of the yard and brand b to another area of the yard, both of which receive full sunlight. she waters the area with brand b daily; she waters the area with brand a every other day. at the end of the study, mina concludes brand b is more effective in growing strawberry bushes. is mina's conclusion valid? explain why or why not.