Which parts of the body act as levers? a. muscles b. joints c. bones d. veins

The answer is "c. bones".

Muscles and bones act together to frame levers. A lever is an unbending pole (for the most part a length of bone) that turns about a rotate (more often than not a joint). Switches can be utilized with the goal that a little power can move a substantially greater power. This is called mechanical advantage.

Levers can likewise be utilized to amplify development, for instance, when kicking a ball, little withdrawals of leg muscles deliver a significantly bigger development toward the end of the leg.

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

there are no contact forces mentioned on the list of choices that you've provided.