Old in age; typically used respectfully to describe older people.
“An elderly man is feeding pigeons near the fountain.”
“There's an elderly couple walking hand in hand along the path.”
This is the polite, standard word to use for older people in Task 3 descriptions — avoid saying 'old people,' since 'elderly' sounds more natural and respectful in spoken English, which examiners notice in your word choice.
Synonyms: older, aged, senior