Scientists use tissue cultures to study possible medicines that can be used to treat cancer patients. What is one benefit of this procedure? Patients do not receive harmful or ineffective medication.
The cultured cells are not in their normal environment.
Doctors know how to treat all types of cancer.
One tissue culture can be used for all cancer patients.

A. Patients do not recieve harmful or ineffective medication.

Explanation:

Scientist use tissue cultures to study possible medications for the patients so that the patients aren't put in harms way to test a drug that would not work or be harmful.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.