Final answer:
d) Golgi apparatus. The Golgi apparatus is the cellular structure most likely affected by a mutation inactivating an enzyme involved in the modification of sugars associated with glycoproteins.
Step-by-step explanation:
The cellular structure most likely affected by a mutation inactivating an enzyme involved in the modification of sugars associated with glycoproteins is the Golgi apparatus.
The Golgi apparatus is responsible for modifying, sorting, and packaging proteins and lipids for transport in the cell. It is involved in the modification of sugars associated with glycoproteins, which are proteins that have sugars attached to them. The Golgi apparatus adds or modifies the sugar molecules on glycoproteins, allowing them to have specific functions.
When the enzyme involved in the modification of sugars associated with glycoproteins is mutated and inactivated, it would impair the Golgi apparatus's ability to carry out this function effectively, leading to abnormalities in glycoprotein modification.