Answer the following question given this paragraph: 

The various emissions will differ considerably in their ability to go through matter, known as their penetrating ability . The α-particle has the least penetrating power since it is the largest and slowest emission. It can be blocked by a sheet of paper or a human hand. Beta particles are more penetrating than alpha particles, but can be stopped by a thin sheet of aluminum. Of the three basic types of emissions, gamma particle are the most penetrating. A thick lead shield is required to stop gamma emissions. Positrons represent a special case in that they annihilate when they come in contact with electrons. The collision of a positron and an electron results in the formation of two gamma emissions that go 180 degrees away from each other.


Q: Of the three basic types of radioactive emissions, what particle is the most penetrating?


A:
gamma