Question

"The ＿＿＿ cyclists who ＿＿＿ each other nodded ＿＿＿ heads in acknowledgement."

Answer 1

This sentence is a general statement which requires to be filled with an adjective for cyclists, pronoun and verb.

Thus, the correct sentence would be: The racing cyclists, who passed each other, nodded their heads in acknowledgement.

Another sentence could be: The aged cyclists, who recognized each other, nodded their heads in agreement.