The idea that having a good cry do you (53)_______ is a very old one and now it has scientific validity since recent research into tears has shown that they (54)_______ a natural painkiller c
The idea that having a good cry do you (53)_______ is a very old one and now it has scientific validity since recent research into tears has shown that they (54)_______ a natural painkiller called enkaphalin.
A. contain
B. retain
C. hold
D. keep