Write the Boolean function in its minimal sum of products and minimal product of sums form:

a$.$ F$=(7,13,14,15)$

b$.$ F$=(1,3,4,6,9,11,14,15)$

c$.$ F$=(1,4,561112131415)$

d$.$ F$=(1,3,4,5,7,8,9,11,15)$