Which of the following assertions are correct?
(i) A neutron can decay to a proton only inside a nucleus
(ii) A proton can change to a neutron only inside a nucleus
(iii) An isolated neutron can change into a proton
(iv) An isolated proton can change into a neutron
A. `(i),(ii)`
B. `(ii),(iii)`
C. `(i),(iv)`
D. `(ii),(iv)`
