Answer
$\beta^{+}$ decay is not favored.
Work Step by Step
The radioactive decay series of Figure 30–11 starts with U-238, which has many more neutrons than protons. It is above the line of stability shown in Figure 30–2.
A $\beta^{+}$ decay effectively converts a proton into a neutron, moving farther from the line of stability. So this process is not favored.
