Hello,
It's D! hope I helped.
Beta decay is very complex phenomena in natural radioactive decay. There are 3 types of Beta decay.
B+ decay (Beta plus or Beta positive or positron decay):
is the conversion of a proton into a neutron plus a positron and an electron neutrino.
B- decay (Beta negative or Beta nought):
is the conversion of a neutron into a proton plus an electron and a electron antineutrino.
Note: a positron is the a positive electron or the antiparticle of the electron.
Hope it helps
67.8 turns needed by the secondary coil to run the bulb.
<u>Explanation</u>:
We know that,



For calculating number of turns

Given that,



We need to find the number of turns in the secondary winding
to run the bulb at 120W 
Firstly find the secondary voltage in the transformer use, 






Now, finding the number of turns in secondary coil. Use, 




The number of turns in the secondary winding are 67.8 turns.