If old mountains are worn down over the course of millions of years, what is one of the primary reasons that mountains still exist?

a.

new mountains are created through tectonic and volcanic activity.

b.

new mountains are created from decomposition of plants and animals.

c.

new mountains are created from leaf litter.

d.

new mountains are created through city development.

(select all the correct choose each statement that is scientific. - the opinions of randomly selected participants in a survey prove the idea that global temperatures are not increasing on earth. - the universe's average temperature and rate of expansion support the idea that it began as one super-dense and hot mass 13.8 billion years ago. - ocean tides are caused by the uneven gravitational pulls of the moon and sun on different parts of earth. - human life is more valuable than other forms of life on earth because humans are more intelligent than other organisms.