Given the task definition, example input & output, solve the new input case.
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").
Example: Fact1: a plant requires sunlight to grow, Fact2: Plants to avoid are fast-growing vines that can take over an area in no time., Question: What requires sunlight in order to take over an area? (A) spores (B) fish (C) plants (D) humans (E) pods (F) Oak (G) opossums (H) coral
Output: C
This is a good example. Based on the facts plants require sunlight in order to take over an area.

New input case for you: Fact1: a graduated cylinder is used to measure volume of a liquid, Fact2: For test cylinders without graduation marks, a manual calibration method has to be used., Question: graduation markings are used to measure the what of a liquid (A) viscocity (B) size (C) flow (D) volume (E) density (F) smell (G) Decibels (H) tube
Output:
D