What is the largest lead margin when Schweitzer has 55% and Jones is not an option?
CREATE TABLE table_47387 (
    "Poll Source" text,
    "Dates administered" text,
    "Democrat: Brian Schweitzer" text,
    "Republican: Roy Brown" text,
    "Libertarian: Stan Jones" text,
    "Lead Margin" real
)
SELECT MAX("Lead Margin") FROM table_47387 WHERE "Democrat: Brian Schweitzer" = '55%' AND "Libertarian: Stan Jones" = 'not an option'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What is the largest lead margin when Schweitzer has 55% and Jones is not an option? ### Input: CREATE TABLE table_47387 (
    "Poll Source" text,
    "Dates administered" text,
    "Democrat: Brian Schweitzer" text,
    "Republican: Roy Brown" text,
    "Libertarian: Stan Jones" text,
    "Lead Margin" real
) ### Response: SELECT MAX("Lead Margin") FROM table_47387 WHERE "Democrat: Brian Schweitzer" = '55%' AND "Libertarian: Stan Jones" = 'not an option'