The answer is: [D]: "higher" .
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Note:
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Choice: [A]: "more high"; — is grammatically incorrect at all costs.
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Choice: [B]: "highest" ; — is the "superlative" — NOT the "comparative".
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Choice: [C]: "more higher"; — is grammatically incorrect at all costs.
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Choice: [D]: "higher" — is the comparative form and is grammatically correct.
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To make reasonable decisions on using natural resources and taking steps to prevent the pollution of large corporations.
Sidebars,glossary's and photographs and bolded words can help you out
Approach an adult such as a high school counselor. Inform them of the situation. Then, after the adult consults with the friend, I would approach him/her and help them out with whatever they are going through. I'd tell them that I'm there for them and try to help to get them to stop.