Final answer:
The shoot apical meristem develops into both the (Option A) stem and leaves as the seedling becomes a sprout, playing a critical role in the plant's primary growth and the potential development of branch shoots.
Step-by-step explanation:
When a seedling develops into a sprout, the shoot apical meristem develops into the stem and leaves. The shoot apical meristem is responsible for producing leaf primordia that eventually develop into leaves, and also contributes to the elongation of the stem. As the plant grows, this meristem continues to produce new tissues, contributing to the primary growth of the plant. Additionally, the shoot apical meristem may leave behind bud primordia in the axil of each leaf, which can potentially grow into branch shoots under the right conditions.