In the nuclear reaction provided:
\[ ^{35}{16}\text{S} \rightarrow \text{blank} + ^{35}{17}\text{Cl} \]
S (sulfur) is transforming into Cl (chlorine) while maintaining the same mass number (35). This indicates that a neutron is being converted into a proton, which is a typical process when beta radiation is emitted.
In beta decay, a neutron is transformed into a proton, and a beta particle (which is an electron) is emitted. In this case, since sulfur is changing to chlorine with the emission of a beta particle, the type of radiation involved is:
b. Beta radiation.