Stroma is what's connecting the stack of thylakoids (granum) with each other
The answer is C. i just completed a worksheet and i got the answer correct hope it helps:)
They use it to react carbon dioxide with water to make a sugar called glucose. The glucose is used in respiration, or converted into starch and stored. Oxygen is produced as a by-product. This process is called photosynthesis.
At sites of seafloor spreading along divergent plate boundaries, this crust is separated into parallel bands of rock by successive waves of emergent magma. When Earth's geomagnetic field undergoes a reversal, the change in polarity is recorded in the magma.
Source: https://kids.britannica.com/students/assembly/view/194471