Given the task definition and input, reply with output. 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: a tape measure is used to measure length, Fact2: Length The Base unit for length in the metric system is the meter ., Question: What is used to measure the base unit of the metric system which is the meter? (A) solid, liquid, gas (B) A laser (C) A measuring cup (D) bottom of feet (E) A tape measure (F) focusing a lens (G) Time and energy (H) A level

E