Final answer:
The tank with a cylindrical body and a hemispherical dome on top is still considered a cylinder, so the answer is option 1) Cylinder.
Step-by-step explanation:
The shape of the tank you're describing is composed of two parts: a cylindrical section and a hemispherical dome on top. The cylindrical section is basically a cylinder, while the top portion is a hemisphere. When these two parts are combined, the overall shape is still considered a cylinder for simplicity because the dominant shape is the cylinder, and other parts like the dome are considered as modifications to it. Therefore, the answer to what shape the tank is would be option 1) Cylinder.