Radioisotopes tell scientists that earth is how old? a. 65 million years b. 500 million years c. 4.5 billion years d. 13.4 billion years

*will mark brainliest* which of the following best describes a viral infection, such as the common cold? a. virus grow and develop in the body. b. virus are living organisms. c. viruses require host cells in the body. d. viruses can be treated with antibiotics.

Structures in cells that carry out specific functions.

Which experiment would most likely contain experimental bias