Final answer:
Calcium (Ca²⁺⁺) is the most electropositive among the given choices because the electropositive character generally increases down a group, and it is higher in metals than in nonmetals like chlorine. The correct option is B.
Step-by-step explanation:
The electropositive character of an atom is its ability to donate electrons. Among the given choices Li²⁺⁺, Ca²⁺⁺, Al³⁺⁺, and Cl⁻, calcium (Ca²⁺⁺) is the most electropositive. The electropositive character increases as we move down a group in the periodic table.
Lithium (Li), being in the same group as calcium but higher up, is less electropositive than calcium. Aluminum (Al³⁺⁺), although it has a higher charge, is less electropositive because it belongs to a group that is to the right of calcium's.
Chloride (Cl⁻), which is an anion, is not electropositive at all; it is electronegative, as it tends to accept electrons rather than donate them. The correct option is B.