Question 1
How are the cell walls of collenchyma thickened?
The right answer is the one marked above.
At the corners only, so the wall is unevenly thickened. Extra cellulose fills the angle where three cells meet, bracing the join while the flat parts of the wall stay thin.
Uniform thickening describes sclerenchyma. Writing only that collenchyma has a thick wall describes both tissues and identifies neither.