Grapes Growing on a Vine Are Observed to Shrink Slightly

Grapes growing on a vine are observed to shrink slightly during the day, only increasing in size at night. This might be because:

A) photosynthesis to produce sugar occurs in the light, but respiration and therefore the growth of new cells occurs mostly in the dark.
B) developing fruits, such as grapes, transpire a lot of water to stay cool.
C) during the day, transpiration pulls on the water in the whole plant, causing the grapes to shrink slightly.
D) in leaves, phloem flow to growing "sinks" only occurs when the stomata are closed because the transport capacity of the xylem is too small to supply water for both transpiration and phloem flow.