Tetanus is a(n):
a. muscle contraction of sustained force resulting from repeated action potentials.
b. contraction where the muscle does not change length.
c. contraction caused by a single action potential.
d. contraction that slowly increases in force.
e. abnormal muscle contraction.

a. muscle contraction of sustained force resulting from repeated action potentials.

Explanation:

Tetanus is a symptom consisting of the constant contraction of one or more muscles. This can be caused by diseases or other physiological conditions that cause an increase in the frequency of action potentials that promote muscle contractions. Thus, the contractions overlap each other and consequently the muscle remains in a condition of constant contraction.

d i think its   answer d

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.