Which of the following is an example of an abab design? half of the subjects receive one treatment and the other half are not treated. all subjects received one of two treatments. a subject is observed and treated. a subject is observed both before and after two exposures to the treatment.

Option D, A subject is observed both before and after two exposures to the treatment.

Explanation:

In A-B-A-B design the alphabets have following meaning

a)First A – It is the baseline value or the value measured before treatment

b)First B – It is the treatment measurement

c)Second A  - It is the withdrawal of treatment  

d)Second B – It is the reintroduction of treatment  

The second A is known as the reversal phase in which the intervention is withdrawn to see if the target behavior returns to the baseline behaviour

Thus , there are two measurements involved one before the intervention and second after the intervention

Option D is correct

i think it is dna, i'm not totally sure but i think it might be.

question: which statement best describes the different properties of metals?

answer: they are shiny and bend without breaking.

since metals have certain characteristics properties, they include the following: they are ductile, malleable, shiny, hard, lustrous, flexible and they are good conductor of heat and electricity. so therefore, metals are not dull and they are not non-flexible as listed. instead, they are shiny and flexible.

hope this , have a good day. c;