Buffers are substances that help resist shifts in pH by (From the close reading exercises) A. releasing H+ to a solution when acids are added.

B. donating H+ to a solution when bases are added.

C. accepting H+ from a solution when acids are added.

D. both donating H+ and accepting H+.

Buffers are substances that help resist shifts in pH by both donating H⁺ and accepting H⁺ (option D).

Explanation:

A buffer is a chemical substance capable of balancing the pH of a solution, when the balance is altered by the addition of an acid or a base. They are also called cushioning solution, and can be formed by an acid and its base conjugated, with a specific range of action.

The presence of a buffer in a solution has the ability to release hydrogen ions (H⁺) or accept them, helping to balance the pH, in the presence of a base or an acid, respectively. That is, a buffer can yield H⁺ to a solution when there are few or accept H⁺ when its content is high.

The other options are not correct because:

    A. Buffers do not release H+ into a solution when acids are added, but accept them.

     B and C.  Giving up H+ to a solution when bases are added or accepting H+ from a solution when acids are added are effects that buffers can potentially do, which is described in the text above.

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