Given a scientific passage and an answer, generate a question for the given answer.

[Q]: Passage: The alkaline earth metals include beryllium, magnesium, calcium, strontium, and barium. Strontium and barium react with air and must be stored in oil. Answer: alkaline earth metals
[A]: Beryllium, magnesium, calcium, strontium, and barium are classified as what type of metals?

[Q]: Passage: Identify evidence for electroweak unification. The quarks in a particle are confined, meaning individual quarks cannot be directly observed. Are gluons confined as well? Explain. Answer: directly observed
[A]: The quarks in a particle are confined, meaning individual quarks cannot be what?

[Q]: Passage: Hydrocarbons may form straight chains, branched chains, or rings. Ring-shaped hydrocarbons are called cyclic hydrocarbons. Answer: cyclic hydrocarbons
[A]:
What are ring-shaped hydrocarbons called?