If you picked up a basalt rock which was shaped like a teardrop it could be a

If you picked up a "basalt rock" which was "shaped like a teardrop", it could be a "volcanic bomb".

Explanation:

When there is a volcanic eruption, the pieces of molten magma are thrown into the air. The gravitational force acts on it to pull it down in such a way that while coming down, the pieces take up the shape of a teardrop. These pieces, for the sole reason that they are shaped like a bomb and are erupted out of volcanoes, are called volcanic bombs.

I’m confused ///: : : :

Answer (d) the greenhouse effect is primarily caused by car and trucks;