Which three phenomena occur during a double-slit experiment and support the wave model of light? A. The light passes through the slit
B. Bright areas appear on the screen
C. Light bends around the edges of the slit
D. Dark areas appear on the screen

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current

i'm assuming that the correct answer is indeed the first one/ "a"..

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3