SC Archive | Re: Records from the latter half of the 19th century

Records from the latter half of the 19th century show that in 1876 in Westbridge County there were 1,200 landowners, nearly 12 percent of the state landowner population,three times as many as 1852.

A three times as many as 1852
B three times as much as 1852
C triple what it was in 1852
D triple the figure for 1852
E thrice the number that was recorded in 1852

I understand that adverb cannot modify nouns.
But how can we identity thrice as adverb and triple as adjective.

Please help