Does the stroma nd the thylakoid membranes have the same function in the chloroplast

No they do not have the same process but they are very close and work in function with each other

The Stroma is the colorless fluid surrounding the grana (or Granum) and enzymes in the process of photosynthesis is embeded in the stroma and also the thylakoid membranes

Thylakoids are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. They normally stack up in stacks called Granum and the Stroma surrounds

The answer is c the potato slice shriveled because water moved out of the slice into the salt solution