[Grammar] who/that

[Ashiuhto]

I am confused by the relative pronoun in the sentence below. According to grammar rules, if there is a 'who' before a relative pronoun, then the relative pronoun should use 'that' to replace 'who'. However, here if the relative pronoun uses 'that', it lays a false scent with 'hat that'. So, which is acceptable, who or that?

Who was the boy with a conical hat ____________ (who, that) crawled through the ladder in this photo from 50 years ago?

 

[EnglishFix]

Who was the boy with a conical hat who crawled through the ladder in this photo from 50 years ago?

This is how I would say it.
Because the phrase "crawled through the ladder" refers to the boy...not the hat.

Sometimes "that" can be used instead of "who" for a phrase that describes a person, but in this case "who" is the best because "who" can only mean a person and not a thing.

 

[philo2009]

According to grammar rules, if there is a 'who' before a relative pronoun, then the relative pronoun should use 'that' to replace 'who'.

This is not a rule, merely a tendency of natural usage.