Which supplement is commonly used as an alternative energy source for those who follow a carbohydrate$-$restricted nutritional strategy?

Question $81$ options:

a$)$

Pea protein

b$)$

Rice protein

c$)$

Long$-$chain triglyceride $($LCT$)$ oil

d$)$

Medium$-$chain triglyceride $($MCT$)$ oil