Which of the following decreases the reliability of results from a clinical trial?
a. an obsolete medical treatment
b. a double-blind technique
c. a short observation period
d. a voluntary enrollment plan

The best answer to the question states above is letter C. A short observation period.

 A scientist's primary concern in a clinical trial is the patient's safety, there fore short observation decreases the reliability of results from a clinical trial

When a virus infects a host cell, it uses the cell's machinery to make copies of its own genetic material in a process called replication. finally, during the process of self-assembly, that protein shell and the copies of the virus's genetic material are assembled into new viruses.