Final answer:
Fluorine can form only one covalent single bond since it has just one unpaired electron in its valence shell and needs only one more to satisfy the octet rule.
Step-by-step explanation:
The largest number of covalent single bonds that can be formed by fluorine is one. Fluorine has seven valence electrons, with one unpaired electron available for bonding. To achieve a filled valence shell and satisfy the octet rule, which is particularly true for nonmetals in the second period of the periodic table like fluorine, fluorine can form one covalent single bond by sharing its unpaired electron with another atom's unpaired electron.
This leads to a diatomic molecule of fluorine (F2), in which each fluorine atom has one bonding pair and three lone pairs of electrons. Therefore, the correct answer is (d) 1.