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

 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

succession returns a disturbed

ecosystem to a more stable state. this is also classified into two (2) types:

primary succession and secondary succession. the primary succession arises when

a new land is transformed and a bare rock has been exposed providing an environment

that can be occupied for the first time. while, secondary succession occurs

when a previously occupied environment was disturbed that kills much of all its

community

explanation: