Answer
$\beta -, \alpha, \beta +$.
Work Step by Step
a. The mass number is the same and the charge has gone up by one. The nucleus emitted a $\beta -$ and an antineutrino.
b. The mass number went down by 4 and the charge went down by two. The nucleus emitted an $\alpha$.
c. The mass number is the same and the charge has gone down by one. The nucleus emitted a $\beta +$ and a neutrino.
