This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

[EX Q]: Passage: Modern electrification systems take AC energy from a power grid which is delivered to a locomotive and converted to a DC voltage to be used by traction motors. These motors may either be DC motors which directly use the DC or they may be 3-phase AC motors which require further conversion of the DC to 3-phase AC (using power electronics). Thus both systems are faced with the same task: converting and transporting high-voltage AC from the power grid to low-voltage DC in the locomotive. Where should this conversion take place and at what voltage and current (AC or DC) should the power flow to the locomotive? And how does all this relate to energy-efficiency? Both the transmission and conversion of electric energy involve losses: ohmic losses in wires and power electronics, magnetic field losses in transformers and smoothing reactors (inductors). Power conversion for a DC system takes place mainly in a railway substation where large, heavy, and more efficient hardware can be used as compared to an AC system where conversion takes place aboard the locomotive where space is limited and losses are significantly higher. Also, the energy used to blow air to cool transformers, power electronics (including rectifiers), and other conversion hardware must be accounted for. Question: What nowdays electrification systems can use?
[EX A]: DC motors which directly use the DC or they may be 3-phase AC motors

[EX Q]: Passage: Poverty is a good indicator of the rate of infectious diarrhea in a population. This association does not stem from poverty itself, but rather from the conditions under which impoverished people live. The absence of certain resources compromises the ability of the poor to defend themselves against infectious diarrhea. "Poverty is associated with poor housing, crowding, dirt floors, lack of access to clean water or to sanitary disposal of fecal waste (sanitation), cohabitation with domestic animals that may carry human pathogens, and a lack of refrigerated storage for food, all of which increase the frequency of diarrhea... Poverty also restricts the ability to provide age-appropriate, nutritionally balanced diets or to modify diets when diarrhea develops so as to mitigate and repair nutrient losses. The impact is exacerbated by the lack of adequate, available, and affordable medical care." Question: Why does living in poverty raise your risk of diarrhea?
[EX A]: from the conditions under which impoverished people live

[EX Q]: Passage: This apparatus may be made of hemp or a synthetic material which retains the qualities of lightness and suppleness. Its length is in proportion to the size of the gymnast. The rope should, when held down by the feet, reach both of the gymnasts' armpits. One or two knots at each end are for keeping hold of the rope while doing the routine. At the ends (to the exclusion of all other parts of the rope) an anti-slip material, either coloured or neutral may cover a maximum of 10 cm (3.94 in). The rope must be coloured, either all or partially and may either be of a uniform diameter or be progressively thicker in the center provided that this thickening is of the same material as the rope. The fundamental requirements of a rope routine include leaps and skipping. Other elements include swings, throws, circles, rotations and figures of eight. In 2011, the FIG decided to nullify the use of rope in rhythmic gymnastic competitions. Question: What other requirement is there for the rope?
[EX A]:
The rope must be coloured, either all or partially and may either be of a uniform diameter or be progressively thicker in the center