What is crystal?.give any example

A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.Example- Snowflakes, diamonds, and table salt.

Examples of everyday materials you encounter as crystals are table salt (sodium chloride or halite crystals), sugar (sucrose), and snowflakes. Many gemstones are crystals, including quartz and diamond. There are also many materials that resemble crystals but are actually polycrystals

Explanation:

a crystal is a piece of a homogeneous solid substance having a natural geometrically regular form with symmetrically arranged plane faces.

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.