The stage of reasoning makes it possible to do simple sums but not use reversible operations. -formal operations thought beings at about age eleven and is the first time child's thinking can be said to be , and .

The stage of pre-conceptual thought is characterised by thought and operation.
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jupiter is mainly composed of hydrogen and helium just like a star. spectral analysis of jupiter has revealed that in addition to hydrogen and helium, the planet is made of water, methane and ammonia. those elements are in trace amounts. the core of the planet is thought to contain some rock and metallic hydrogen. i hope this will give you the answer to your question! : d

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."