Chemistry · S and p Block Elements

The nine most common elements in the Earth's crust are roughly 46% oxygen, 28% silicon, 8.3% aluminium, 6.9% iron, 2.4% calcium, 2.5% sodium, 2.4% magnesium, 2% potassium, and 0.61% titanium. Silicon and Aluminum are the two most abundant elements in the Earth's crust. Silicon is the most abundant element overall, making up about 28% of the Earth's crust by mass, while Aluminum is the third most abundant element, constituting around 8% of the crust.  

Boron and Aluminum are not the most abundant elements in the Earth's crust. While they are present, they are not among the most abundant. 

Calcium and Magnesium are important elements in the Earth's crust, but they are not the most abundant. 

The nine most common elements in the Earth's crust are roughly 46% oxygen, 28% silicon, 8.3% aluminium, 6.9% iron, 2.4% calcium, 2.5% sodium, 2.4% magnesium, 2% potassium, and 0.61% titanium. Silicon and Aluminum are the two most abundant elements in the Earth's crust. Silicon is the most abundant element overall, making up about 28% of the Earth's crust by mass, while Aluminum is the third most abundant element, constituting around 8% of the crust. 

"All" is not a correct answer in this context because it does not specify the elements. As discussed, Silicon and Aluminum are the correct choices.