Final answer:
Effective communication is classified as a soft skill, highly valued for promoting collaboration and understanding in various professional settings.
Step-by-step explanation:
The ability to communicate effectively is d) a soft skill. Soft skills are personal attributes that enable someone to interact effectively and harmoniously with other people. Since effective communication involves both expressing ideas and understanding the needs and ideas of others, it is considered a soft skill. This skill is highly valued across all professions and industries because it facilitates collaboration and understanding, driving individual and organizational success.