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D. 3H2O

Explanation:

An atom is the smallest unit of matter that has the characteristics of a chemical element. It consists of protons, neutrons, and electrons - small electrically charged particles.

They make up molecules - electrically neutral groups of two or more atoms connected by chemical bonds. Multiple molecules that consist of two or more different atoms make up a chemical compound.

The chemical compound that has nine atoms is 3H2O. Here, we have three molecules of water. Each molecule consists of three atoms - two hydrogen atoms and one oxygen atom. This means that three of these molecules have a total of nine atoms.

a

explanation:

many plants naturally reproduce this way, but it can also be induced artificially. horticulturalists have developed asexual propagation techniques that use vegetative plant parts to replicate plants. success rates and difficulty of propagation vary greatly. monocotyledons typically lack a vascular cambium and therefore are harder to propagate.