
Answer:
Corrective maintenance β costs due to modifying software to correct issues discovered after initial deployment (generally 20% of software maintenance costs)
Adaptive maintenance β costs due to modifying a software solution to allow it to remain effective in a changing business environment (25% of software maintenance costs)
Perfective maintenance β costs due to improving or enhancing a software solution to improve overall performance (generally 5% of software maintenance costs)
Enhancements β costs due to continuing innovations (generally 50% or more of software maintenance costs)
Explanation: