In this task, you are given two facts, and a multiple-choice question. Based on the given facts, answer the question with index of the correct option (e.g, "A").

Fact1: insulated material can be used for keeping warm, Fact2: An insulated cup with a cover is great for keeping beverages warm., Question: How do you keep a cup hot? (A) less water (B) electricity (C) heat energy (D) adding heat (E) energy usage (F) insulation (G) squeeze (H) energy
F

Fact1: Bivalves feed on plankton and nonliving organic matter., Fact2: Mussels are bivalve mollusks., Question: What feeds on plankton and nonliving organic matter? (A) barnacles (B) mollusks (C) animals (D) the Sun (E) sharks (F) graptolites (G) bacteria (H) dogs
B

Fact1: a vehicle is used for transportation, Fact2: Most bigger cities require efficient and adequate public transport systems., Question: What do most bigger cities require? (A) fluoride (B) slides (C) vehicles (D) desire (E) specialized (F) backbones (G) tap water (H) religion
C