Explanation:
The ionic character of a compound is determined by the difference in electronegativity between the elements involved. The greater the difference in electronegativity, the more ionic character the compound will have.

Electronegativity:
Electronegativity is a measure of an atom's ability to attract electrons towards itself in a covalent bond. It is a property of an atom and is based on its position in the periodic table. The electronegativity values range from 0 to 4, with 0 being the lowest and 4 being the highest.

Comparison of Electronegativity:
To determine the compound with maximum ionic character, we need to compare the electronegativity values of the elements involved in each option.

a) Na and C:
The electronegativity of Na is 0.93 and the electronegativity of C is 2.55. The difference in electronegativity is 1.62.

b) Cs and F:
The electronegativity of Cs is 0.79 and the electronegativity of F is 3.98. The difference in electronegativity is 3.19.

c) Cs and I:
The electronegativity of Cs is 0.79 and the electronegativity of I is 2.66. The difference in electronegativity is 1.87.

d) Na and F:
The electronegativity of Na is 0.93 and the electronegativity of F is 3.98. The difference in electronegativity is 3.05.

Conclusion:
From the above comparisons, we can see that option b) Cs and F has the highest difference in electronegativity, which indicates maximum ionic character. Therefore, the compound formed from Cs and F will have the maximum ionic character.