Match List I of the nuclear processes with List II containing parent nucleus and one of the end products of each process and then select the correct answer using the codes given below the lists :
List I
List II
P.
Alpha decay
1.
$_8^{15}O \to _7^{15}N + ...
Q.
{\beta ^ + } decay
2.
_{91}^{238}U \to _{90}^{234}Th + ...
R.
Fission
3.
_{83}^{185}Bi \to _{82}^{184}Pb + ...
S.
Proton emission
4.
_{94}^{239}Pu \to _{57}^{140}La + ...