Answer:
C. It compares the frozen crystals to delicately lacy snowflakes having an unexpected strength
Step-by-step explanation:
A metaphor is a figure of speech that directly compares two things that aren't alike but do have something in common providing clarity or showing similarities between two ideas.
The metaphor used in this excerpts compares the H20 (water) molecules when frozen organize themselves to form hexagonal crystals that are like elicately lacy snowflakes having an unexpected strength