Answer:
option d. Hypertrophy and neural facilitation.
Step-by-step explanation:
Strengthening of muscles or say the capacity to generate force of muscles can be improved by training the muscles with the help of neural facilitation and hypertrophy.
Neural facilitation is the process that transfers the stimuli to the muscles
To overcome the deficiency of oxygen during training of muscles, the muscles grow in size. this phenomena is termed as Hypertrophy.