To answer this question, we have to look for the oxidation numbers of each of the elements.
Oxidation number of calcium is +2, which means that it is likely to lose 2 electrons.
Oxidation number of potassium is +1, which means that it is likely to lose 1 electron.
Oxidation number of Boron in +3, which means that it is likely to lose 3 electrons.
Oxidation number of Fluorine is -1, which means that is is likely to gain 1 electron.
Oxidation number of Phosphorus is -3, which means that it is most likely to gain 3 electrons.
Oxidation number of Sulfur is -2, which means that it is most like to gain 2 electrons.
It means that the final answer is:
Potassium - Lose 1
Calcium - Lose 2
Boron - Lose 3
Fluorine - Gain 1
Sulfur - Gain 2
Phosphorus - Gain 3