Similarities between glacier and geyser

The correct answer is:

The only similarity is that they are both glacier and geyser made of water.

The explanation:

1- geyser:

A geyser is a natural phenomenon that features a gushing fountain of water and/or steam being emitted from a hole in the ground. Such eruptions often occur on a periodic basis

2- A glacier:

is a huge lump of water ice and nothing more. If a glacier melted fast enough it would become a river.

So, both of them made of water.

i believe the answer is a.