Explanation:

- The underlined segment in the sentence uses "large then," which is incorrect. The correct comparative form should be "larger than."

- Option 1: larger than I had - This option uses the appropriate comparative form "larger" and correctly pairs it with "than."

- Option 2: No substitution required - This option suggests the original sentence is correct, but it contains a grammatical error.

- Option 3: largest to what I have - This option incorrectly uses "largest" (a superlative form) and awkwardly phrases the comparison.

- Option 4: large then I have - This option repeats the original error "then" instead of "than" and includes another error by using the present tense "have."