Final answer:
The phrase 'Fourteen-year-olds, for instance, are not allowed to drink, to marry, to vote, to serve on juries or even to drive.' best supports the Supreme Court's stance against the death penalty for minors.
Step-by-step explanation:
The phrase from the text that best supports the answer to Part A, which is related to the Supreme Court's decision that the death penalty may not be applied to those who were under 18 when they committed a crime, is option B: "Fourteen-year-olds, for instance, are not allowed to drink, to marry, to vote, to serve on juries or even to drive." (Paragraph 14). This phrase emphasizes minors' lack of legal responsibilities and privileges as adults, highlighting the recognition of their different levels of judgement and responsibility, which aligns with the Supreme Courts stance on the cruel and unusual punishment of juveniles.