Convection currents in the Earth's crust cause volcanoes.

true or false

It's false, purely because the crust in the Earth are cold and brittle, and that prevents the convection currents, which represent one of the three main types of heat transfer, to appear. Moreover, when this temperature difference exists, we can say that hot fluids rise and cold fluids sink, and then currents, or movements are created.

It should be false, the crust is eventually cold and brittle for convection of currents to occur. The convection currents that is usually located at the magma drive plate tectonics. Warm produced from the radioactive rot of components somewhere down on the inside of the Earth makes magma in the aesthenosphere.