Final answer:
A student best prepared for phonics instruction can segment and blend a word's phonemes, a crucial skill for reading and spelling.
Step-by-step explanation:
A student who has mastered the skill of being able to segment and blend a word's phonemes is best prepared to begin explicit phonics instruction. This skill involves the understanding of how words break down into individual sounds and how these sounds can be put together to form words. This foundational understanding is crucial for the development of reading and spelling skills and indicates readiness for more advanced phonics learning.