Final answer:
The synonym for 'Multitudinous' is A) 'Abundant' as they both mean existing in large numbers or being plentiful.
Step-by-step explanation:
The synonym for "Multitudinous" is A) Abundant. Multitudinous means existing in or being in large numbers, which essentially carries the same meaning as abundant, whic also means present in high quantity, plentiful or numerous.
The options B) Punishment, C) Shimmering, and D) Shaky do not align with the meaning of multitudinous and therefore are incorrect synonyms.