• 選手せんしゅ — athlete, player
• 選択せんたく — selection, choice
• 選挙せんきょ — election
• 当選とうせん — being elected
• 再選さいせん — re-election
• 選えらぶ — to choose
• 選定せんてい — screening, selection

選 combines the 辶 (movement) radical with 巽 (phonetic and meaning element). Together they suggest "moving toward" or "picking" a direction, which naturally developed into the idea of choosing or selecting. It’s often used in social, political, and personal decision-making contexts.

好きすきな 本ほんを 選えらんでください。
Please choose your favorite book.

彼かれは 市長しちょうに 選出せんしゅつされました。
He was elected as mayor.

The kun-yomi えらぶ is used in casual and spoken contexts, like "choose a gift." The on-yomi セン appears frequently in compound words like 選手 (player) or 選挙 (election).