The most accurate answer to why colonial economies were successful during the period of Salutary Neglect is:
B. Colonies increased intercolonial commerce due to the decreased British regulation of colonial trading restrictions.
During Salutary Neglect, which lasted from the early 18th century until the mid-1760s, the British government was lenient in enforcing trade laws, allowing the colonies to engage in greater levels of trade and commerce with each other and outside entities. This independence enabled the colonies to develop their economies more robustly, fostering intercolonial trade that contributed to their overall economic success.